JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 319R ATOMIC SPECTROMETRY UPDATE - INDUSTRIAL ANALYSIS METALS CHEMICALS AND ADVANCED MATERIALS John Marshall* and John Carroll ICI Wilton Research Centre P.O. Box 90 Middlesbrough Cleveland UK TS90 8JE James S. Crighton BP Research and Engineering Centre Chertsey Road Sunbury on Thames Middlesex UK TW16 7LN Charles L. R. Barnard Department of Physical Sciences Glasgo w Caledonian University Cowcaddens Road Glasgo w UK G4 OBA Summary of Contents 1. Metals 1.1. Ferrous Metals and Alloys 1.2. Non-Ferrous Metals and Alloys Table 1. Summary of Analyses of Metals 2. Chemicals 2.1. Petroleum and Petroleum Products 2.1.1. Crude Oil and fractions 2.1.2. Fuels 2.1.3. Lubricating Oils 2.2. Organic Chemicals and Solvents 2.2.1 Chemicals 2.2.2.Solvents 2.2.3. Catalysts Table 2. Summary of the Analyses of Chemicals 2.3. Inorganic Chemicals and Acids 2.4. Nuclear Materials 3. Advanced Materials 3.1. Polymeric Materials and Composites 3.2. Semiconductor Materials 3.2.1 Silicon-based materials 3.2.2. Gallium-based materials 3.2.3. Cadmium mercury telluride- and indium phosphide-based materials 3.3. Glasses Ceramics and Refractories 3.3.1. Glasses 3.3.2. Ceramics and refractories Table 3. Summary of the Analyses of Advanced Materials This Atomic Spectrometry Update is the latest in an annual series appearing under the title of ‘Industrial Analysis’. The structure of the review is broadly the same as in previous years. The range of techniques which can now be used routinely in an industrial laboratory has probably never been wider.In some respects the selection of the most appropriate technique to address a given problem is becoming harder with every passing year. In the field of plasma spectroscopy there have been significant developments in the design of laser spark and glow discharge sampling cells which are clearly beginning to make an impact on the wider field concerned with the direct analysis of solids. The explosion of interest in the use of chromatography in all its various forms for preconcentration extraction separation and speciation in conjunction with both AAS and AES (using ICP and MIP sources) continues unabated with the sensitivity and selectivity of ICP-MS being used to particular advantage. High resolution ICP-MS promises still further advances in analytical performance in this area.Equally progress made in the XRF arena with preconcentation technology and total reflection geometries has demonstrated that the technique may be applied to good effect in the analysis of liquids and in non-destructive depth profiling applications once considered the domain of surface analysis techniques. It may not be possible for every laboratory to have all the techniques available but it would appear that many existing techniques are being developed to the stage where each is able to address a wider range of applications. 1. METALS This section of the review covers the analysis of ferrous and non-ferrous metals and their alloys by analytical atomic spec- * Review Co-ordinator to whom correspondence should be trometry. Applications are summarized in Table 1 and the principal areas of development to appear during the period of this review are described in detail below.addressed.320R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 Table 1 SUMMARY OF THE ANALYSES OF METALS Technique; atomization; Element Matrix analyte form* Ag Ag Silver electroplating baths Lead oxide AA;-;L AA;F;L Sample treatmentlcomments Reference 941464 94/95 1 Ammonium oxalate (5%) was used as leaching agent Sample solutions were diluted to 1-10 pg ml-' before determination. Relative determination error was Sample was dissolved in HCl (1 +4)-HNO (1 t 4 ) and analysed without any separation or masking procedures; the characteristic concentration reported was 16 pg for 1% absorption and the determination range was 0.0002-0.01 YO Sample analysed as soluble and insoluble fractions Films containing 15 at.% Al; the "Al' image was 4% (P=O.95) 9313540 9411 94 94/2789 spatially correlated with the nickel image A1 Tin-based alloys AA;ETA; L A1 Steel AE;-;L A1 Aluminium-doped Imaging S1MS;-; molybdenum-nickel S superlattice films As Nickel-based alloys AA;ETA;L Solid samples of nickel-based alloys were 93/3355 decomposed with a mixture of HC1-HNO (4+ l) the resulting solution was heated nearly to dryness and the residue was dissolved in about 2 ml of distilled de-ionized water.Recovery 99 + 3 %; detection limit 0.30 ng g-' Chemical interferences of matrix elements and some metalloids were studied and eliminated. Certified standard reference materials were used to verify the method Interferences from nickel removed by the addition of iron( 111) and acids Excess of sodium diethyldithiocarbamate eliminated interference effects of complexing agents on Au atom formation Scattered source lines were used as an internal standard.for assessing the K value in gold jewellery. The samples were excited by an annular Am source with an activity of 18.5 Gbq. The best deviation was 0.29% Preconcentration of Au with trioctylphosphine oxide (TOP0)-impregnated resin Flow-injection selective on-line fibre column was used for separation. and preconcentration. The detection limit was 0.2 ng ml-I of Au and the RSD was 6% ( n = l l ) for 1 ngml-1 and 2.2% (n=7) for 80 ng ml-' solutions Adsorption preconcentration of Au and Pt from water onto a mercapto-acetamide resin gave > 95% recovery In situ dissolution of a solid sample by addition of 25% HNO nitric acid in a cup-in-tube atomizer was compared with slurry injection Sputter depth profiling with 2.5 5 and 8 keV Ar and Xe positive ions None Steel and vacuum cast super AA;F;G alloys As 93/41 17 As Au AE;ICP;G AA;F;L 941300 9 313 3 9 7 Steels and nickel alloys Jewellery XRF;-$ Au 9313840 Au Au Ore AA;F;L AA,F;L 9314123 9411 1 Ores and metallurgical samples Au Water AA;-;L 941209 Au High purity silver AA;ETA;L 941744 Gold-platinum Coins Steels SIMS; - ;S Au Au B 941145 1 9412379 93/3996 EDXRF and AE;ICP;L PIXE;-;S Samples were extracted into a solvent system of 2-ethyl-1,3-hexanediol in xylene ( 10% mlv); the detection limit was 0.04 pg g-' Aerosol particles produced for the sparking process were collected and dissolved in aqua regia Thin films of boron nitride AISI 316 Austenitic Stainless Steels were doped with 10 and 50 ppm B and then thermally treated in dissociated ammonia Small amounts of B and P were determined precisely by line analysis without pre-sputtering Determination of bismuth in steels and nickel alloys at the 0.1-10 pg g-' level comparison between FI-HGAAS and ETAAS See As.Depth profiling of C in tantalum thin films was investigated using a Cs primary ion beam Sample was weighed into a 150 ml beaker mixed with HCl and heated. It was then mixed with HNO and evaporated to near dryness and re-dissolved in HNO and water Sample was dissolved in aqua regia and re-diluted in 1 + 1 HNO,.The detection range was 1-10 pg g-' The RSDs were in the range 9.3-14.3% and recovery was 98-102% B B Steel Steel AE;ICP;L XPS;-;s 941598 9411500 B Bi Cast iron Steels and alloys SIMS;-;S AA;HG;L 9411 547 9313943 Bi C Steels and nickel alloys Tantalum thin films AE;ICP;G SIMS;-;S 941300 9411389 A A;ETA; L Ca Steel 94/c 1941 Stainless steel AA;ETA;L Cd 9313566JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 321 R Table 1 (continued) Element Matrix c1 Refractory metals Technique; atomization; analyte form* Sample treatmentlcomments Reference IDMS;-;S Chlorine was separated by precipitation with Ag; 94/1317 negative C1- thermal ions were produced in a double filament ion source. The detection range of 0.006 and 0.1 pg g-' depended on the variation of the blank values 1,lO-phenanthroline complex ion on ammonium- tetraphenylborate-naphthalene adsorbent.The complex was quantitatively retained on the adsorbent in the pH range 2.4-9.7.The RSD was 0.62% ( n = 8 ) for a sample containing. 10 pg of Co and the detection limit was 0.0012 pg ml-' contribution coefficients of Co and Cu for the different layers Preconcentration on a column of 4-( 5-bromo-2- pyridylazo)-l,3-diamino benzene and ammonium tetraphenylborate supported on naphthalene as adsorbent and then dissolved in DMF. Calibration was linear up to 18 pg of analyte in 5 ml of final solution for which RSD was 0.83% chamber and a plasma generated by an argon fluoride excimer laser focused to a spot size of 0.65 mm2 resulting in a power density of 1.2 x 109 W cm-' Two industrial ferrochromiums (fecr-L with a low carbon content and fecr-H with a high carbon content) samples were prepared by re-melting in a high frequency furnace.The samples were ground to below 100 pm particle size determination of Fe Ni and Cr in stainless steel led to signals that were not rectilinearly related to element concentration. Artificial neural networks were evaluated as a multivariate calibration tool for modelling the iron<hromium-nickel system Films were created on target in the sputtering device consisting of a nickel sheet on which a few titanium chips were placed Cs+ primary ions were used in conjunction with the detection of CsHe' . Ions to study concentration depth profiles of He in A160Mn40 alloy. Helium concentrations down to about 100 ppm were measured at a moderately low sputtering rate of 0.5 nm s-' extracted with HC1 filtered and diluted to 100 ml acidified with HCl and diluted 50 ml.An aliquot (1 ml) was mixed with 1 ml of 10% potassium thiocyanide 0.4 ml of 5% zinc acetate 1 ml of 10% tin chloride and 2.2 ml of 10% NaOH. The Hg vapour was absorbed with 10% potassium permanganate solution in 1 mol 1-' H'SO,; recoveries ranged from 90 to 108%. The RSD was 4.5% Samples were dissolved in HF and HNO NH,OH was found to be an effective matrix modifier for the determination of K. Detection limits were 0.005 ppm of Na and 0.006 ppm of K in 0.5 g samples. The RSDs were > 3% for 0.25 ppm of Na and >4% for 0.14 ppm of K additions approach; the analysis took approximately 30 min including sample dissolution and matrix separation was not found to be necessary Matrix interferences were eliminated by the addition of both EDTA and SrCl,.The detection limit was 0.50 ng g-' and the recoveries ranged from 97+4 The sample was preconcentrated as its SIMS signals were used to determine the Samples were mounted in an evacuated sample XRF or AE;ICP;S Inter-element effects in the simultaneous XRF The sample was dissolved with HN03 (3 + lo) The results were calculated using the standard to IO4_+2% Samples were electrolytically prepared and the reproducibility for electrolysis and FI determination was 3-5% c o AA;F;L 94/67 c o c o Copper SIMS;-;S AA;F;L 9411499 9411693 Cr Low alloys steels AF;F;G 9411135 Cr Ferrochromium 9412 190 Cr Stainless steel XRF;-;S 9412255 9313576 9411354 H He Titanium-nickel alloy Aluminium-manganese AE;ICPL SIMS;-;S Crude gold AA;CV;L 9411050 High-purity tantalum A A;ETA;L 9412567 K Li Cast iron and steel AE;ICP;L 941953 Nickel-based Alloys Metal alloys AA;F;L AA;F;L 9313356 94/2 10322R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 Table 1 (continued) Technique; atomization; analyte form* SIMS;-;S Sample treatment/comments Reference Element Matrix Mn Galvanized steel SIMS depth profiling examination of the cause of 9411 548 zinc-iron alloy outburst microstructures and the composition of the protective Fe,AI layer which contained Mn Samples were dissolved in dilute aqua regia filtered and the filtrate evaporated to near dryness with 5 ml of concentrated HC1; the cooled residue was shaken with acid (4+6) and 0.5% ethyl dodecylthioacetate solution in butyl acetate and the organic phase was back extracted with 10 ml of 1% ammonia solution for 45 min Steel powder was dissolved in hot aqua regia cooled filtered and mixed with Sr (30' and CsN+ polyatomic ions were used to reduce matrix effects in the detetermination of these elements in a heterogeneous matrix A glow discharge lamp was modified to high vacuum standard and gave a BEC of 0.017%.This corresponded to a detection limit of 5 ppm for 1% RSD of the background Carbon powder was used as buffer; the ratio of the sample to powder was 1 2; the standard series were prepared by using 9 1 tungsten cobalt powder containing Na2S04 anhydride and carbon powder 9411231 .4s for K Sample was digested with aqua regia-H,O with heating and the digest was mixed with 2 ml of H,PO and 8 ml of H2S04 then heated to fuming.The cooled solution was treated with 20 ml of 20% tartaric acid boiled until it became clear then diluted to 100 ml with water. Recoveries were 97.2-101.3 Yo See As Mo Cast iron A A;ETA;L Steel Metal alloys AE;ICP;L SIMS;-;S 9412090 9313725 Mo N S teel AE;GD;S 9313994 N Na Tungsten-cobalt hard alloy AE;-;S 941 214 Na Nb High-purity tantalum S teel AA;ETA;L AE;ICP;L 94/2 5 67 9412285 Ni Ni Steel and vacuum cast super Ore and steel AA;ETA;L AA;F;G alloys 93/41 17 941206 NH400 was used as a matrix modifier to enhance the sensitivity of the method to 2.2 x lo- pg ml-' per 1 Yo. The relative error was k 3.5% nitride and acryl) were examined to determine the Ni load and depth distribution Layered structures in optical flats (quartz boron As for N Titanium samples were bombarded by Cs+ primary ion and intensities of negative secondary ions were measured.The ion intensity ratio varied linearly with 0 concentration with a correlation coefficient of 0.999. The RSD was < 12% for the whole range of 0 concentrations studied Ion exchange chromatographic conditions optimized to remove matrix interferences. Linear calibration range was 2.00-50.00 pg ml-' of P. RSD for steel sample analysis was 0.02-0.05 (n = 3 P = 0.95) As for B A laser pulse was used to atomize material from the surface with a spot diameter of 50-300 pm. The detection limit was 0.05 ppm Spectral interferences from lead on Pd were avoided by optimization of the temperature programme to volatilize the matrix prior to analyte antomisation As for Au As for Au As for Au Laser excited atomic fluorescence spectrometry in a graphite furnace.The detection limits were 20 fg Te and 10 fg Sb; equivalent to 0.01 ng 8-l in nickel based alloys by direct solid sample analysis for a lmg solid sample The linear dynamic ranges of the calibration curves were six and seven orders of magnitude for Sb and Te respectively RSD was 7% As for As Electrolytic slimes were measured in a concentration range of 5 x 1OP6-20% m/m; detection limit of 0.003% Ni Metallized layered structures TXRF; - ;S 941661 0 0 Metal alloys Titanium SIMS;-;S SIM S; - $3 9313725 9412837 Steel AE;ICP;L P 941942 Cast iron Steel SIMS;-;S AF;laser;S P Pb 9411547 9411 144 Pd Lead AA;ETA;L 9313363 Pd Pt Pt Sb High purity silver Water High purity silver Nickel alloys AA;ETA;L AA;ETA;L AF;ETA;S AA;-;L 941744 941209 94/74! 9313366 AE;ICP;G AA;ETA;L Sb Sb Steels and nickel alloys Copper-molybdenum 941300 9411654JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 323 R Table 1 (continued) Element Matrix Technique; atomization; analyte form* Sample treatment/comments Reference Se Nickel AF;F;G Se and Te were separated from the nickel matrix and 94/98 other interference elements by lanthanum hydroxide coprecipitation and detected simultaneously by hydride generation. Detection limits of Se and Te were 0.45 pg 8-l and 0.4 pg g-I and RSDs were 5.4 and 4.0% respectively Nickel and palladium used as a mixed matrix modifier which gave improved sensitivity when the ashing temperature was increased leading to a reduction in interference effects The sample was digested by heating with 1 ml of HNO evaporated to near dryness and cooled.The residue was treated with 1 ml of concentrated H2S0 heated to fuming and then cooled treated with A13+ and adjusted to pH 6 mixed with 2 ml of ethanolic 5% quinolin-8-01 and filtered. The precipitate was washed with hot H20 and the filtrate and washings were combined mixed with 10 ml of HCI and H 2 0 and diluted to 50 ml. The detection limit was 0.04 ng ml-' of Se. Recoveries ranged from 92-98% and RSD were 26.5% Samples weighed accurately into a polythene beaker and 5 ml of water 6 ml of HCl and 2 ml of HNO were added.The mixture was heated until the dissolution was complete cooled dissolved in 0.5 ml of HF and diluted to 100 ml. Palladium as a chemical modifier had a substantial effect on the Si atomization reducing the atomization temperature to 2500°C Interferences in the generation of the hydride were removed by addition of oxygen to the carrier gas stream. Detection limit of 0.05 pg I-' in a 500 pl sample; precision range 1-3% RSD Citric acid was used as a matrix modlfier As for Sb As for Se Sample was digested in HCl-HNO (4 + 1 ) heated nearly to dryness and the residue dissolved in deionized H20. For T1 solutions were treated with NH,; Te alloy solutions were diluted to 10 ml with 0.2% HNO,. The detection limits for T1 and Te were 15 and 35 pg 8-l. The addition of a palladium modifier improved the detection limit but decreased accuracy precision and recovery Samples were dissolved and separated from matrix elements by ion-exchange extraction and solvent extraction with a benzene solution of Amberlite LA-2.It was back-extracted into a 0.5 mol 1-' HF-1.2 mol 1-1 HCI mixture As for TI Organic and inorganic acid interferences can be eliminated by operating the flame at its optimum N20 C2H2 ratio Interferences of the concomitant elements were eliminated by a strict calibration of the flame Direct Sample briquetting gave accuracies of 0.19% for Mn in ferromanganese 0.3% for Si in ferrosilicon 0.28% for Cr in ferrochromium residue with sodium peroxide. The principal source of error was interlaboratory bias. Proposals were made for further work in the field of plain and alloy steels Sample was decomposed with HCl and H,02 within a few minutes.The solution obtained was diluted and mixed with a lanthanum internal standard solution and HC1 was added Recoveries were better than 9.7%. RSDs were 0.04-0.35°/~ (n= 5) electrothermal microsample system. Detection limits were reported of 3.3 1.4 and 1.7 ng ml-' for Cu Zn and Cd respectively Acid dissolution and treatment of the insoluble Sample solution was introduced with an AA;ETA;L AF;F;L 941 1629 94/27 12 Se Se Nickel alloys Pure copper 9412202. Si Low alloy steels AA;ETA;L 9313969 Sn Steel AA;HG;L 9412 1 1 9313366 94/98 94f2557. Sn Te Te Te Iron and steel Nickel alloys Nickel Nickel-based alloys AA;ETA;L AF;ETA;S AF;F;G AA;ETA;L 9314078 A A;ETA;L Ti High Alloy Steels & Iron 94/25 57.9313484 A A;ETAL AAF;L T1 Nickel-based alloys V Ferrous alloys 9313485 AA;F;L V Steel 941352 9313891 Zn Electroplated steel sheet Various ( 3 ) Ferroalloys AE;GD;S XRF;-;S 9313997 Various (10) Steel AE;ICP;L 94/23 AE;ICP;L Various (4) Rare earth-iron magnetostriction alloys AE;MIP;L 941107 Various (3) Steel324 R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 Table 1 (continued) Technique; atomization; Element Matrix analyte form* Various Austenitic stainless steels AE;ICP;L Various (3) Steels and nickel alloys AE;ICP;G Various (10) High purity chromium AE;ICP;L Various (21) Refractory metals Various Al/Si alloys Various (10) Tungsten alloy chips Various ( 5 ) Iron and steel Various (8) High-purity titanium AE;ICP;L AA;F;L AE;ICP;L AF;F;L MS;ID;S Various (4) Iron and steel AA;ETA;L Various High purity iron AE;ICP;L Various (10) Steel X-Ray;-$ Various (13) Pt-Rh and Pd-Rh alloys AE;ICP;L Sample treatment/comments samples were electrochemically treated in oxalic acid Matrix element interference effects were removed by addition of Fe"' and acids to sample solutions Ten trace elements (As Co Cu Fe Mn Ni Ti V Zn and Zr) in chromium metal and chromium disilicide were quantitatively coprecipitated with lanthanum hydroxide and separated from the chromium matrix preconcentrated in acidic peroxide solutions; up to ten-fold sensitivity enhancement was observed microwave oven (330 W) in inorganic acids with oxidizing agents taking 45-180 and 10-15 min respectively; the two methods were compared coefficients of variation were 3.3-10.5%; recoveries were 95.3-106.9% Sample was dissolved in aqua regia evaporated to near dryness mixed with HC1 (1 + l) thiourea and ascorbic acid.Recoveries were 90-110% and the RSDs were 1-3% Thermal ions formed by a single- or double-filament ion source except for thorium where an ICP was applied. The detection limits obtained were U Th=0.07; Cu=I; Cd=1.7; Ni=4; Pb=6; and Fe=35 ng g-' LO mg iron and steel specimens used to yield LODs of 0.00004 O.OOO1 0.0004 and 0.0002% for Cr Cu Mn and Ni respectively elements by complex formation and preconcentrated with cation exchange resins examined to aid instrument calibration 50 pg of yttrium (internal standard) and 10% HC1; RSDs were <6.1% hon-sensitized SUS 304 and 316L stainless steels All elements with cationic chemistry were Samples were heated conventionally or in a Detection limits were less than 0.6 ppm and Samples were dissolved and separated from matrix Heterogeneity of standard reference materials Sample was dissolved in dilute HC1 and mixed with Reference 9412 1 6 941300 941571 941733 941822 941 1 2 3 8 9411259 9411292 9411832.9412078 9412342 94/27 13 1.1. Ferrous Metals and Alloys Much of the activity in the year under review has been focused on altering the form of the analyte and/or its mode of presen- tation to the instrument. This follows a trend observed in previous reviews indicating the continuing search for methods that are either interference free or that incorporate interference removal steps prior to the analytical measurement.Hydride generation offers considerable advantages both in separating the analyte element from the matrix and as a means of preconcentration. This approach has been employed for the determination of As Bi Pb Sb and Sn in iron and steel using non-dispersive AFS (94/1259). Recoveries were reported to be in the range 90-110% and the RSDs were 1-3%. No inter- ference effects were caused by matrix elements in the steel. A miniaturised continuous running cell with platinum electrodes has been used to generate hydrides for AAS (94/557). The anode and cathode compartments of the cell were separated by a Nafion membrane. The gaseous reaction products hydrides and hydrogen formed at the cathode were rinsed out of the cell with the catholyte (typically dilute sulfuric or hydrochloric acid) and separated from the aqueous solution in a subsequent membrane gas-liquid separator prior to detection by AAS in an electrically heated quartz cell.Sulfuric acid was found to be particularly suitable as an anolyte since after separation of the oxygen formed at the anode the acid can be re-used and only needs to be changed after 40-50 h of operation. The small geometric dimensions of the cell allowed the flow rate of the catholyte to be extremely low. Therefore the consumption of expensive high-purity acids was found to be lower than in conventional HG systems. The technique was found to provide high sample throughput used low sample volumes (100 pl) and is compatible with FI operations. The technique was applied to the determination of As in steels.Interference effects resulting from the presence of transition metals were found to be largely eliminated using this system. The application of ETAAS to the relatively difficult deter- mination of Ca in steels has been described (94/C1941). Approximately 0.2 g of sample was dissolved in a mixture of hydrochloric and nitric acids and the solution was heated until near dryness. The salts were redissolved in nitric acid and diluted with water prior to analysis by ETAAS. It is well known that contamination is a major problem for this determi- nation. While it is possible to use a hydrofluoric acid sample treatment and plastic laboratory ware it was claimed that using the method described glassware could be used through- out the procedure without introducing contamination.The graphite tube was repeatedly heated at 2400°C to remove Ca present in the substrate as an impurity. Peak area (integrated) measurement was applied but it was noted that peak height measurements produced different readings for samples and standards containing the same amount of calcium. It was reported that satisfactory results were obtained using either the method of standard additions or normal calibration procedures.JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 325 R The determination of Si by ETAAS is also difficult as no clearly defined optimum atomization temperature has been reported for the element that would facilitate accurate analyt- ical measurement. Silicon is easily combined with graphite or oxygen to form refractory silicon carbide or volatile silicon oxide during the heating process in the graphite ETA tube.Thus poor sensitivity and bad accuracy are often encountered in the determination of Si by ETAAS. The use of a palladium salt as chemical modifier for the determination of silicon by ETAAS has recently been reported (94/2202). The instrument response curve for Si in the presence of the palladium modifier exhibited an absorbance plateau between 2450 and 2750 "C for the atomization temperature. The optimum atomization temperature for the determination of Si was found to be 2500°C which resulted in a method yielding better precision with improved sensitivity. The method was validated by the analysis of NIST SRMs 361 362 and 363 Low Alloy Steels.Whilst AAS is often used for the determination of trace elements it is also possible to determine higher concentrations of elements by the use of less sensitive spectral lines. This approach has been used in the analysis of steels multi- component alloys and electrochemically isolated structural constituents (93/3998). These materials contained high concen- trations of Co Cr Cu Mn Mo and Ni. The evaluation of a number of secondary and less sensitive lines was carried out for these elements and the ranges of practical application with appropriate dilution factors were reported. Avoidance of chemical pre-treatment is possible if direct methods such as solid sampling can be adopted. Laser ablation ICP-MS is increasingly being seen as a viable alternative approach for the analysis of metal samples (94/C1881). In this work a direct comparison was made of the performance of laser ablation ICP-MS with GD-MS on the same spectrometer system.Laser ablation was found to provide a superior lateral spatial resolution of20 microns and the need for a particular sample geometry was obviated. Laser ablation of solid samples has also been used in conjunction with a microwave-induced plasma emission source in a low pressure argon atmosphere (93/3959). The highly desirable goal of matrix independent analysis was found to be feasible by combining time-gated detection of the emission spectra with internal standardization of the line intensities. When applied to the determination of binary samples such as chromium/iron and brass and steel copper and aluminium it was found to a first approximation that low absolute and relative detection limits could be achieved with a single laser shot.Interest continues in the use of spark ablation as a means of sample introduction to the ICP. Pneumatic nebulization and spark ablation sampling systems were compared for the deter- mination of B in steels by ICP-AES (94/598). The pneumatic nebulization was preceded by a one-step microwave digestion procedure developed specifically for determining total boron content using diluted aqua regia and high pressure vessels. The stability of discharge sampling during the spark ablation- ICP process was tested by plotting B and Fe emission intensit- ies versus sparking time. Using pneumatic nebulization a detection limit for boron of 2.6 pg g-' was obtained and overall RSD values of 1-3.5% were reported.For spark ablation the detection limit for boron was 0.65 pg g-' and the overall RSDs were in the range 0.5-1.5%. The analytical performance of spark ablation ICP-AES was found to be significantly better than the pneumatic nebulization sample introduction mode. The application of high-resolution Fourier transform spec- trometry has been described for the study of excitation of Cr and Fe in a microwave-boosted GD (94/40). A Grimm-type GD source was used with and without supplementary micro- wave boosting using various cathodes (Al Fe Cr and Cu) with argon or helium as the carrier gas. Studies of true line profiles allowed unambiguous line identification even when major changes in relative intensities occurred.Further infor- mation was presented on the effects of the excitation conditions on the Fe and Cr spectra using relative intensity measurements on a very large number of spectral lines. The results for Fe and Cr emphasized that any excitation temperatures deduced from data for a limited number of lines are meaningless. Differences were observed between the ionic spectra for these two elements and it was suggested that charge-exchange exci- tation was a significant factor for Fe but not for the Cr spectrum. The grade of a particular steel is dependent partially on these concentrations and a method for accurately measur- ing small concentrations of Mn in the presence of excess iron could be of potential use in steel-grade verification. Such a method has been proposed to overcome difficulties inherent in quantitative analysis by EDXRF of samples that contain widely different concentrations of two or more elements having similar atomic numbers (94/2369).Results obtained by com- puter simulations and simple experiments show that significant increases in the intensities of the X-rays emitted by the lower- 2 element relative to those from the higher-2 element can be achieved through the proper design of a primary-source second- ary fluorescence excited system (using iron or cobalt) and a chromium detector window filter. The system was used to distinguish between iron samples with a Mn content of <2% by weight. Typically more than forty chemical elements are required to be analysed in ferrous metallurgy and most of these have to be determined during the production process. Optical and X-ray spectroscopy techniques are most commonly used for determinations of this type.A new method which may have some potential for on-line monitoring of steel production and metal-plating has been described based on liquid-arc/spark excitation (94/962). An arc was struck with the surface of the of the liquid sample and the resultant plasma was observed using a fibre optic coupled to an AE spectrometer. At the present stage of development the system has been used only in laboratory experiments on ions dissolved in solution but linear intensity relationships with concentration have been established. It was anticipated that a liquid flow through cell could be developed to allow the on-line application of the technique.Sample preparation is a critical stage of the production analysis process as it is important to present homogeneous samples to the instrument. A comparison of commercially available high-frequency induction heaters used for sample re-melting has been carried out (94/2384). The samples were heated in ceramic crucibles and were cast using a centrifugal process. This type of sample preparation pro- cedure was applied to cast iron ferro-alloys metal powders rods and other structures. 1.2. Non-ferrous Metals and Alloys There were relatively few abstracts received during the period under review which described work which could be considered truly novel. A summary of analytical methods for non-ferrous metals and alloys is given in Table 1.Nickel has often been used successfully as a matrix modifier for the determination of As by ETAAS. Consequently it might be expected that the measurement of As in nickel-base alloys would be relatively free of interference effects (93/3355). Although it was found that the nickel matrix did indeed prevent charring losses for As serious interferences were still found to exist. It was noted that the reproducibility of the measurement was much improved if trivalent As was used for standard calibration solutions. Consequently after the sample had been decomposed with a mixture of nitric and hydrochloric acids potassium iodide was used to reduce AsV to As". This method was found to give satisfactory results for As present in SS CRM 346A IN 100 alloy at the 51 ng 8-l level. The detection limit for the method was reported to be 0.3 ng g-l.Two other methods involving digestion of the sample alone and with the addition of hydrazine failed to achieve full recovery of As. A further paper by the same authors concerning the determination of Mg in CRM IN100 and Inconel alloy326R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 718 nickel base alloys by FAAS may also be of interest (93/3356). Laser excited jluorescence spectrometry has been applied to the quantitative determination of P and Te in nickel alloys (94/C1949). Fluorescence measurements were carried out in a pressure controlled graphite furnace atomizer using both solid and liquid samples. Accurate analytical data were obtained for P and Te if the sample was digested in acid prior to the determination.A solid sampling approach was also evaluated and good quantitative results for Te were only obtained by operating the furnace at atmospheric pressure. At reduced pressures instrument calibration was unsatisfactory as a result of differences in sensitivity between Te atomized directly from the solid and analyte atomized from the aqueous solution standard. Incomplete atomization of P prevented the application of solid sampling to this determination under any pressure condition. Copper is a metal which is readily available in high purity and is often used as a material for testing new procedures for the direct analysis of metals. In an interesting development an atmospheric pressure MIP has been employed to directly sample copper wire (94/C1980).The wire was inserted through the end of the quartz plasma tube allowing the plasma to interact with the surface and this has been found to result in ablation of Cu. Microscopic inspection of the wire revealed surface changes and residues from the wire were found on the quartz tubing. Studies were also being made of the effect of applying a potential across the plasma to enhance ablation. The work is clearly at an early stage but it is to be hoped that further details of this device will be published during the coming year. A new scanning X-ray analytical microscope has been applied to high precision analysis and imaging of small samples including 1000 pm copper mesh (94/C1997). A maximum sample stage area of 150 x 150 mm was scanned at 2 pn resolution using a scintillation detector for the transmitted X-rays and a high purity silicon detector for X-ray fluorescence.Graphic representations of the transmitted X-rays and of as many as 31 elements could be obtained simultaneously. A range of copper compounds and alloys have been studied by XRF to investigate the effect of oxidation state and concen- tration of Cu on the spectra produced (94/978). It was found that the Lp/La emission intensity ration for Cu varied with the change of copper concentration in the sample as well as with the change in chemical state. The intensity ratio was found to vary in the order Cu" > Cu' > Cu metal or alloy with low concentrations giving higher ratios than high concen- trations of Cu.The behaviour was found to arise from self- absorption effects. It was stated that the determination of the chemical state of copper using the L line ratio only was risky because of concentration and matrix effects. A laboratory-constructed cathodic sputtering atomizer has been characterized for direct analysis of solid metal samples (94/49). The effects of changes in applied power discharge gas pressure and flow rate on AAS and AES signals obtained from a jet-assisted cathodic sputtering atomizer were investigated. The absorbance of Ni sputtered from brass samples and the emission intensities of a Cu resonance line (CUI 324.8 nm) and an ion line (CUII 224.7 nm) were measured. With increasing flow rate of the discharge gas (argon) the emission intensity of the Cu resonance line reached a maximum and then decreased with further increase in the flow rate whereas the emission intensity of the ion line continued to increase.This behaviour was attributed to self-absorption. High resolution Fourier trang'rm spectroscopic measurements indicated self- reversal of the resonance line for Cu. A two-element (Cu-Fe) coherent forward scattering resonance monochromator (CFSRM) was developed in which transmission signals for each element were recorded with a single photomultiplier via time-sharing by a gated pulse-counting technique (94/629). The transmittance of the CFSRM for Fe and Cu could be varied separately and correction of stray and leakage light through crossed polarizers was performed. Radiation from a Grimm-type glow discharge lamp with an Fe-Cu alloy cathode (0 2 5 and 10mgg-I Cu) was filtered through the Cu-Fe CFSRM and a linear analytical curve of Cu was obtained. It was anticipated that the two-element CFSRM system could be extended to allow multi-element analysis.Concerns about health and safety in the work place con- ditions requires monitoring of the chemical composition and morphology of welding fume particles and grinding dusts (94/59). Elemental composition and morphology of pure manual metals arc (MMA) welding fumes pure grinding dust and combined fume/dust air samples were collected and deter- mined separately under semi-laboratory conditions. This study was conducted to create a synthetic work situation by combin- ing a grinding period and two MMA welding periods and comparing these results with those obtained during welding in a workshop. A comparison was also made between metal inert gas (MIG) and MMA welding on a Ni-rich alloy.The amount of collected material was determined by weighing the mem- brane filters before and after exposure and element contents were determined by AAS. Other transmission electron microscopy (TEM) filters were used in conjunction with computer-image analysis to determine the amount of collected material and its morphology. The Mn and total Cr contents were lower in grinding dust than in welding fumes and CrV1 in grinding dust were undetectable. Welding shop samples contained 30% less CrV' than those of laboratory samples. A procedure for the simultaneous determination of trace impurities in high-purity chromium metal and chromium disilicide by ICP-AES has been described (94/571). The basis of the method was the selective co-precipitation of the matrix from the analytes.Although chromium(rI1) was quantitatively co- precipitated with lanthanum hydroxide chromate(vi) was not. This different behaviour of chromate(w) was used for the analysis of chromium metal and chromium disilicide. Chromium(II1) was oxidized to dichromate(v1) by fuming with perchloric acid and converted into chromate(vi). Chromium(1n) can be oxidized to dichromate(v1) by perchloric acid or peroxodisulfate. It is difficult however to obtain high- purity peroxodisulfate. Less pure peroxodisulfate will result in increased reagent blanks and therefore higher detection limits.Perchloric acid was used as an oxidizing reagent in this study because pure acid can be easily obtained. Several elements form ammine complexes when ammonia solution is used for pH adjustment. The resulting soluble complexes of trace elements will not be recovered from the coprecipitation solution and this decreases the number of elements to be determined. Sodium hydroxide solution was therefore used to adjust the pH of the coprecipitation solution to pH 11.0 after which ten trace elements (As Co Cu Fe Mn Ni Ti V Zn and Zr) in chromium metal and chromium disilicide were quantitatively coprecipitated with lanthanum hydroxide and separated from the chromium matrix. These trace elements were simul- taneously determined by ICP-AES using matrix-matched cali- bration solutions.A method has been published for the simultaneous determi- nation of Cu Fe Al and Zn in tin solder (93/3539). It was found that it was necessary to perform a preliminary separation of these analytes from the lead and tin matrix. Thus tin was removed as its insoluble hydrated oxide on addition of concen- trated nitric acid and lead was precipitated as the chloride upon addition of hydrochloric acid. It was reported that matrix effects were eliminated when this preconcentration procedure was applied. Finally a universal metals identifier has been described for in situ on-site testing (94/C1970). A compact CCD array optical emission spectrometer has been developed for identifi- cation of metal grades with calibration for up to eight base elements and 17 curve sets.Neural net technology was used to give reliable identification based on a limited set of training data. It was however noted that spectral interferences exist which make line selection a complex matter!JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 2. CHEMICALS 327 R 2.1. Petroleum and Petroleum Products The increasing use of heavy crude oils and ever advancing environmental legislation has led to intensified interest in determination of metals in refinery and petrochemical feed- stocks and characterization of fuels. Table2 provides a sum- mary of work carried out in this field during the review period. There has however been a welcome reduction in the number of papers reporting yet more alternative ways for determination of wear metals in used lubricating oils.2.1.1. Crude oil and fractions Elemental analysis of crude oils is important for a number of reasons. Some elements can cause corrosion problems in plants others can poison refinery and petrochemical process catalysts and most are potential sources of problems in terms of environmental pollution. However there are also beneficial aspects of the presence of trace elements in crude oil in that they can also provide valuable information on petroleum diagenesis migration and accumulation as previously dis- cussed (93/3400). Determination of trace elements in crude oil and fractions can be accomplished using a variety of techniques the most common being XRF ICP-AES ICP-MS and AAS. For example during the review period trace elements in Nigerian crude oils have been determined using EDXRF (94/2413) Ni and V have been determined in Saudi Arabian oil products using ICP-MS (93/3463) and the trace element composition of petroleums from individual wells of the Gyuneshli j e l d have been established using FAAS (94/72).Possibly the most commonly applied technique for elemental analysis of crude oil and products is XRF. The popularity of this technique almost certainly stems from the ease of sample preparation and its inherent freedom from problems associated with element solubility selective volatilization and loss of volatile elements. A typical example is application of EDXRF to determination of trace elements in oil shale (94/1216). In this approach matrix correction was accomplished using empirical coefficients for determination of Ba Co Cr Cu Ni Rb Sn V and Zn.The problem with this approach is that a large number of calibration standards are generally required. One possible way to reduce the number of standards is through use of theoretical calculations based on fundamental param- eters (94/2355). A slight disadvantage is that the method generally requires knowledge of light element concentrations (particularly C H ratios) which can not normally be measured using XRF. However this need not represent a major problem if full characterization of a crude oil is to be carried out since the relevant element concentrations can readily be measured using other analytical techniques. An alternative approach to reducing XRF matrix effects without requiring a large number of standards is to present the sample to the spectrometer as a thin film (negligible absorption/enhancement effects).One such method which has been reported involved mixing approxi- mately 1 g of crude oil with 5 g of IBMK and pipetting 50 pl portions onto a wax ring on a filter paper (94/992). The main problem with this approach is that LODs are significantly degraded due to the small amount of sample analysed. This latter limitation can largely be eliminated by using T X R F . Ojeda et al. (94/2220) have reported LODs of 0.1 0.4 20 and 0.6 pg g-l respectively for determination of Fe Ni S and V in crude oil using this technique. An alternative approach in which the oil matrix is completely decomposed has also been reported (94/1060). In the latter approach 1.3g of crude oil was mixed with 1.1 g MgO and then heated to 270°C with stirring for 20 min.The residue was then pulverized and pressed into a disc for determination of Cr Cu Fe Mn Ni V and Zn using EDXRF. The advantage of this approach is that matrix effects are reduced since the hydrocarbon matrix is completely destroyed however the method is not suitable for determi- nation of volatile analytes (e.g. S). A similar approach has also been applied to prepare samples for analysis using GDMS ( 94/2 809 ). If lower LODs are required then ICP-AES or ICP-MS are the techniques most commonly applied. Trace element analysis of petroleum products can be accomplished using these tech- niques by direct aspiration of hydrocarbon solvents into the ICP but this can give rise to several problems including plasma instability interference from molecular bands and ions and degradation of analytical performance.Botto (93/3406) has described the use of an ultrasonic nebulizer with desolvation system for analysis of volatile hydrocarbons. The desolvation system gave a substantial reduction in the amount of solvent entering the plasma while the high sensitivity of the ultrasonic nebulizer served to compensate for the degradation in analyt- ical performance caused by residual hydrocarbons. An alterna- tive approach to reducing plasma solvent load is to introduce the sample in the form of a micro-emulsion. This approach has been applied to the determination of Ni and V in petroleum products using ICP-MS (94/2883). Unfortunately the high dilution factors required to form stable micro-emulsions ( 100-500) compromise the excellent LODs which would other- wise be achievable using ICP-MS.It also has been reported that with some modifications ICP-AES can be applied to on-line analysis of high temperature and pressure fossil fuel process streams (94/913). The equipment described consisted of a high power ( 5 kW) Ar/He plasma with a torch which allowed process gas at 650°C to be injected directly into the base and a series of 0.1 m monochromators which viewed the plasma via quartz fibre optics. The ultimate solution to eliminating problems associated with hydrocarbons in ICP-AES (or ICP-MS) when analysing petroleum products is to completely digest the samples prior to analysis. However problems can then be encountered for some elements (eg.S and P) due to loss of volatile components. Two closed vessel digestion techniques have been reported which avoid this problem for the determination of P (93/3706) and S (93/3706,94/573) in crude oil and related materials. In the first approach (93/3706) samples were digested with nitric acid and hydrogen peroxide in a stainless-steel bomb and in the second (94/573) a Parr oxygen combustion bomb was used. There have been several reports during the review period regarding characterization of crude oil and fractions using chromatographic techniques with element specific detectors based on atomic spectrometry. Kosman (93/3975) has reviewed applications of GC-AES for simultaneous multi-element (C C1 H N 0 and S) determinations for petroleum and related materials (e.g.simulated distillation) while Pretorius et al. have used ICP-MS with HPLC (94/1087) and GC (94/2688) for determination of metalloporphyrins. It remains to be seen however whether these techniques will offer significant advan- tages over conventional approaches. Mercury in gas and condensate streams is a major problem in the petroleum industry in view of its tendency to cause embrittlement of aluminium heat exchangers and to poison downstream catalysts. The preparation and performance of sulfurized silicates for mercury elimination in gaseous streams has been discussed (94/1687). In this study AAS together with XRD XPS nitrogen adsorption-desorption and Hg intrusion porosimetry were used for characterization of the new sorbents using commercial sulfurized active carbon as reference.2.1.1. Fuels Most of the work carried out during the review period has been concerned with characterization of fuels and their328 R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 Table 2 SUMMARY OF ANALYSIS OF CHEMICALS Technique; atomization; Element Matrix analyte form* Sample treatmentlcomments Reference cu Kerosine AA;ETA;L 941586 Ga Hi2 Ni Metalloporphyrins Gaseous stream sorbents Gasoline or fuel oil MS;ICP;L AA;-;L MS;ICP;L 9411087 9411687 9313362 Ni Ni Petroleum products Crude oil MS;ICP;L MS;ICP;L 9313463 9412883 0 0 P Pb Pb Pb Pb Pb Pb Pb Gasoline Gasoline Petroleum products Aviation fuel Alkyllead compounds Organolead compounds Gasoline Kerosene Environmental samples Waste oil AEM1P;L AE;MIP;L AE;ICP;L AE;ICP;L AA;F;L AA;F;L AA;F;L AA,ETA;L LE1;F;L MS;GD;S 941436 9412393 93/3 706 9313406 9313642 93/3988 941228 94/586 94/2394 9412395 Crude oil AEM1P;L Petroleum and bituminoids MS;-;L 9313630 93j3647 PETROLEUM AND PETROLEUM PRODUCTS- As Natural gas AE;MIPG Determination of organoarsine compounds in natural 941c1954 gas using capillary GC-AES.(LOD for arsine = 10 PPW (PCB) and inorganic chlorine in waste oils using temperature programming. LODs were between 0.5 and 10 pg PCB g-' oil depending on degree of chlorination of PCB solutions consisting of propanol-kerosine-0.2% HNO,(aq). Solutions were stable for up to 3 h in an autosampler cup and up to 24 h in a closed flask RPLC-JCP-MS used for determination of gallium porphyrins in coal extracts Study of the efficiency of sorbents based on sulfurized silica for removal of Hg from gaseous streams Gasoline evaporated to <0.5 ml and product mixed with 0.5 g tetralin 1 g Triton X-100 and then made up to 50 g with water.Calibrated using similar blank microemulsion spiked with aqueous standards. (LOD approx 70 pg g-') using 8-hydroxyquinoline. (Recoveries 98-104%; Oil sample (0.5 g) mixed with 0.5 g tetralin and 1 g c1 Waste oil MS;ICP;L ETV-ICP-MS used to differentiate between organic 941278 Kerosine samples stabilized by forming 3-phase Extraction of Ni and V from petroleum products RSDS <4%) of Triton X-100 shaken for 10 min and then diluted to 250 ml. Resulting microemulsion was introduced directly to ICP-MS. LOD was 0.3 pg g-' and RSD better than 5% Determination of total S content and concentration of oxygenated additives in gasoline using GC-AES with 0.1 mm capillary column (complete elution in < 10 min) Determination of oxygenated additives in gasoline using GC-AES.On-line He purification and use of a tangential flow torch with lateral viewing gave 0 selectivities of 4850 1 versus carbon (LOD = 1 ngs-' 0) pressurized stainless steel bomb. Recovery was 98-102% and RSDs around 1.5% for concentrations 0.01 % Sample diluted with toluene and 1% bromine in CHC13 added to decompose alkyllead to PbBr (Conostan stabilizer added to reduce surplus bromine). Prepared samples introduced to ICP using ultrasonic nebulizer Speciation of alkyllead compounds in environmental samples using GC-AAS.Methodology for extraction and derivatization of ionic alkyllead species is described Review (54 refs) covering determination organolead compounds in the environment using GC-AAS (includes tetraalkyllead and ionic alkyllead compounds) Comparison of results with those obtained using stripping potentiometry. Good agreement reported As for Cu LC-LEI used for determination of four organolead species and inorganic lead in oyster tissue Aqueous leachate spiked with enriched isotope and equilibrated. A few hundred pl was then mixed with a conducting host matrix dried homogenized and pressed into a GD cathode. Pb determined using ID-GDMS Comparison of AES with flame ionization and flame photometric detectors for GC characterization of S polycyclic aromatic compounds. AES more effective and economical than FPD Methods for preparation of petroleum and rock samples for isotopic analysis of sulfur.Samples dried with CaCl and hydrogenated over a Pt catalyst. The H,S generated was captured in zinc or cadmium acetate Samples digested with HN03 and Hz02 in aJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 329 R Table 2 (continued) Element Matrix S Petroleum products S Gasoline S Gasoline S Crude oil S Diesel fuel V Gasoline or fuel oil V Petroleum products V Crude oil V Crude oil Various Petroleum products and petrochemicals Various (6) Petroleum products Various Drilling fluids Various Distillation residues Various Crude Oil Various Petroleum products Technique; atomization; analyte form* AE;ICPL AEM1P;L AE;MIP;L AE;ICP;L XRF and MS;-;L MS;ICP;L MS;ICP;L AA;F;L MS;ICPL AE;ICP;L AE;MIP;L XRF;-;L and S AE;ICP;L AA;F;L AE;MIP;L Various Fuel oil XRF;-;L Various Fossil fuel process streams AE1CP;G Various Crude oil Various (7) Oil Various Engine oil Various (9) Oil shale Various Lubricating oil Various Lubricating oil (wear metals) Various (4) Crude oil AAF;L XRF;-;S AE;ICP; L MS;ICP;L XRF;-;L Sample treatmentfcomments As for P but RSDs around 6.6% Quantitative determination of S compounds in FCC gasolines using GC-AES.Compound independent element specific response used for calibration As for 0 Samples digested using Parr oxygen combustion bomb and calibration carried out using simple aqueous standards. (RSDs 1-3%) dilution thermal ionization mass spectrometry and XRF (ASTM method D2622-87) (concentration = 423 _+2 pg g-') Certification of S in SRM 2724 using isotope As for Ni.(LOD approx 50 pg g-') As for Ni Extraction of VV-5,S-methylenedisalicylohydroxamic acid with 0.5 moll-' tributylphosphate in IBMK (LOD down to 0.006 pg ml-l) As for Ni; LOD = 2.52 pg g-' Comparison of performance of ultrasonic nebulizer (with desolvation system) with that of pneumatic nebulizer (with cooled spray chamber) for analysis of petroleum products (particularly volatile fractions) simultaneous multi-element determination of compounds containing C C1 H N 0 and S Method for quantitative analysis of water or oil based drilling fluids containing solid or liquid components dispersed or dissolved in a liquid carrier using XRF and IR Determination of heavy metals using air-Ar plasma and xylene solvent.(RSDs 0.1-7.5%) Trace elements (15-19) determined in crude oils from individual wells of the Gyuneshli field Multi-element simulated distillation using GC-MIP-AES with advanced data processing applied to fingerprinting petroleum derived products Determination of Ca Cr Cu Fe Mn Ni Pb Ti V and Zn in several bunker and sludge oils using TXRF (concentrations in pg g-' range). Method can be used to identify source of waste oil discharges at sea Development of modular ICP-AES system for on-line multi-element analysis of high temperature and pressure fossil fuel process streams. Unique design of torch body allows process gas at 650°C to be injected directly into plasma Sample (0.5-1 g) hot-filtered mixed with 5g IBMK and then three 50 pl portions spotted onto wax ring on filter paper.LODs for Cu Mn Ni and V were 0.14 0.21 0.37 and 0.34 pg respectively Sample (1.3 g) adsorbed onto 1.1 g MgO organic compounds thermally degraded and resulting powder pressed into pellets for EDXRF determination of Cr Cu Fe Mn Ni V and Zn Fluorinated high density polyethylene spray chamber provided intimate mixing of flame gases and sample thereby reducing acetylene requirements and minimizing carbon deposition on burner 4 g pulverized sample (< 200 mesh) pressed directly into 35 mm pellet and analysed using XRF with Rh anode X-ray tube. Detection limits were in the 1-10 pg g-' range for Ba Co Cr Cu Ni Rb Sn V and Zn Routine determination of wear metals in lubricating oil and oily waste ETV-ICP-MS used to measure wear metals (Al Mg and Y) arising from wear of silicon nitride ball bearings TXRF used for determination of Fe Ni S and V in small (mg or pl) samples of crude oil.(LODs 0.1 0.4 20 and 0.6 ppm respectively; RSDs 2-6%) Review of applications of GC-MIP-AES for (LODS 0.6-11.5 pg g-') Reference 9313706 941135 941436 941573 94/26 3 3 9313362 9313463 941345 941288 3 9313406 9313575 9313844 9314007 94/72 9411 3 1 941656 94/91 3 941992 94/1060 9411 100 94/1216 94/1730 94jC1991 94/2220330R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 Table 2 (continued) Element Matrix Technique; atomization; analyte form* Various (1 1) Crude oil and heavy XRF;-;L distillates Various Cooling fluids (wear metals) XRF;-;L Various (6) Metalloporphyrins MS;ICP;L Various Lubricating oil (wear metals) Various Petroleum products AA;F;L MS;GD;S ORGANIC CHEMICALS AND SOLVENTS- As Chinese medicine AA;ETA,L Bi Drugs P i ) Alkaloids AA;ETA;L AA,F;L C Organic compounds AE;ICP;L Tetradecylpyridinium AA;F;L bromide (Cd) c1 Organo-chlorine samples c1 Air AA;ETA;L AE;ICP;G (Co) Cocaine hydrochloride (Co) Cationic surfactants AA;FL AAETA,L c o Cr (CU) Sample treatment/comments EDXRF used to determine As Cd Cu Fe Hg Mn Ni Pb Se V and Zn in Nigerian Crude oils and their heavy end distillates.Concentration range 0-1 10 ppm Determination of Ca Co Cr Cu Fe K Ni Ti and Zn in cooling lubricants (solutions emulsions slurries and oils) using TXRF. LODs were in the range 3-30 pg g-' High temperature GC-ICP-MS used for analysis of porphyrin containing extracts from coal and oil shale.LODs ranged from 0.14 to 0.51 ng for the elements Cu Fe Ni Ti V and Zn Oil (1-2 g) shaken for 3-5 s with 0.4 ml aqua regia and heated at 60°C on ultrasonic bath to dissolve metal. Resulting solution diluted with xylene or IBMK for determination of Al Cr Cu Fe and Pb using FAAS mixed with conducting host and pressed into cathode pin. RSDs of around 5% and good agreement with ICP-AES reported but some problems with polyatomic interferences Samples ashed at low temperature and then residue Sample (0.4 g Liuwei dihuang pills) digested with 4 ml HN03-HC104 and then diluted with water. H3PO4 added as matrix modifier (calibration range 0.05-0.5 pg ml-l) electrode-graphite furnace AAS in pH 1.5 HNO solution. (concentration range 0.3-30 ng ml- ') Indirect continuous flow method for determination of papaverine strychnine and cocaine.( Bi14)- injected into carrier stream containing alkaloids caused precipitation of ion pair (concentrations 1-100 pg ml-') Total organic carbon (TOC) determined by injecting CO gas produced from persulfate oxidation of organic compounds directly into ICP carrier gas. Performance claimed to be comparable to commercial TOC analyser Indirect determination of tetradecylpyridinium bromide by association with the complex ion (CdBr,)'- in water and extraction of the complex into dimethylbenzene Determination of organic chlorine by AlCl molecular absorption spectrometry using a carbon rod furnace Pb 261.417 nm light source and deuterium lamp for background correction chlorinated compounds in air based on capillary air inlet r.f.excited He plasma fibre optics and optical filter. LOD for trichloroethylene in air = Bi in drugs determined by Nafion modified Compact robust system for measuring volatile 1 *PPm Indirect method for determination of cocaine hydrochloride by mixing solution of analyte in CHCl with 5% Co(SCN) evaporating the organic layer to dryness and dissolving Co complex in 5% HNO Indirect method for determination of cationic surfactants in waste effluents and shampoos by formation of ion pair with hexanitrocobaltate(II1) and extraction into dichloroethane. Concentration range 0.1-24 pg ml- ' Sample diluted 1 + 1 with IBMK. Standards prepared by dissolving organometallic salt in 1 + 1 phenol- IBMK. Concentrations 1-10 ppm hardened gelatin sensitized with ammonium dichromate competitive exchange of analyte during preconcentration of Cu( 11) on Nafion modified electrode.Concentration range 13-250 mol 1- ' Phenol AA or AE;F or 1CP;L Dichromated gelatin XRF;-;S Measurement of Cr content of developed and dark Pharmaceuticals (arginine) AA;ETA;L Indirect method for determination of arginine using Reference 94/24 3 9412482 9412688 94/27 11 9412809 9412801 9313575 9412204 9412136 9313531 9411 137 9412130 9411 5 1 941344 9411273 9412241 941230JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 331 R Table 2 (continued) Technique; atomization; Element Matrix analyte form* (CU) Wine (reducing sugars) AA;F;L Sample treatment/comments reducing sugars in wine based on precipitation of Cu,O when Fehling's solution is injected into wine carrier which was directly aspirated.Concentration range 10-110 ng ml-' Indirect method for determination of free fatty acid (FFA) in organism samples by formation of Cu soaps in organic solution of analyte and direct determination of Cu in the organic phase. Concentration range 10-100 nmol FFA drug nitrocaphamum using competitive exchange of analyte during preconcentration of Cu( 11) on nafion modified electrode. Concentration range 0.4- 11 pmol 1- containing 2 g NaCl (simulated stomach solutions). Hg determined using CV AAS Sample (0.4 g) digested with HN03-HzS04-HC10 (4 1 1) and then diluted to 50 ml with water. 2 ml portion of this solution mixed with 2 ml each of SnCI and H2S04 (0.5%) to generate Hg vapour for analysis using AAS HN0,-H,SO,-HClO (4 1 1) and then diluted with water.Calibration range up to 50 ng ml-' Samples diluted in water and method calibrated using standard additions. LOD =0.9 ng ml-' As for K. LOD = 2.3 ng/ml Measurement of distribution properties of Automated system for indirect determination of Indirect method for determination of anti-cancer Samples dissolved in 1 1 of 0.1 mol I-' HC1 Sample (Liuwei dihuang pills) digested with commercial P containing extractants at various pH and ionic strength values using kerosene or benzene solvents which uses an ignition source and minimal fuel gas flows which give transient combustion but will not support a flame. Sensitivity claimed to be higher than conventional FPD 4 ml HN0,-HC104 and then diluted with water.Ni(NO,) added as matrix modifier Calibration range 0.05-0.5 pg ml-' chemical interferences Pulsed flame photometric detector (FPD) described Sample (0.4 g Liuwei dihuang pills) digested with As for Co but AAS showed some evidence of As for P Alkyltin compounds extracted using 0.05 % tropolene in 0.04 mol 1-' HC1-methanol. Extracts cooled in dry icelmethanol bath to remove non-volatile coextractives. Methyl derivatives formed and quantified by GC-AAS. Concentrations ng 8-l Comparison of ICP-MS and flame ionization (FID) for detection of tetrabutyltin tributyltin chloride triphenyltin chloride and tetraphenyltin separated using SFC. ICP-MS LODs were 0.26 0.80 0.57 and 0.20 pg respectively oxovanadium N,N-propylene- bis( trifluoroacetylacetoniminate). (pg LODs) Study of effect of auxiliary gas flow on basic plasma properties under various experimental conditions Study of influence of atomizer type chemical form of analyte and modifier for determination of Cd Co and Pb in CCl CHCI and lY2-dichloroethane.Best results with W impregnated atomizer and Pd matrix modifier improvement in analytical sensitivity in air-CzHz FAAS. Shorter chain length surfactants found to give greatest effect military explosive waste using AAS alongside other chemical and physical tests GC-AES used to characterize isomerism of Several surfactants studied in relation to Analytical scheme for identification of unknown Reference 941703 Free fatty acid AA;F;L 9411 755 Pharmaceuticals (ni trocap hamum) AAETAL 9412800 Medicines Chinese medicine AA;CV;L AA;CV;L 9413 5 3 9412626 Chinese medicine AA;CV;L 9412801 AA;ETA;L 941407 K Acetone 941407 941473 Na P Acetone Commercial extractants AA;ETAL AE1CP;L 94/c 1953 P Various AE;F;G 941280 1 Chinese medicine AA;ETA;L Pb 941 1 27 3 Phenol AA or AE;F or 1CP;L AEF;G AA;F;L Pd 94/c 195 3 941756 S Sn Various Edible oils 9412294 Sn Alkyltin compounds MS;ICP;L 9313503 V Oxovanadium Schiff base AE;MIP;L chelates 9313390 9313410 Various Organic solvents AE;ICP;L Various (3) Chlorinated organic solvents AA;ETA;L 9313414 9313585 Various Surfactants AA;F;L Various Military waste AA;F;L332R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 Table 2 (continued) Technique; atomization; analyte form* AE;MIP;L Element Matrix Various (10) Organometallics Sample treatmentlcomments Reference New detection schemes (recipes) for use with 93/36 10 commercial GC-AES system developed for selective detection of Al B Cr Ga Mn Pd Pt Rh Ti and V MS formation of ion pair with (BiI,)- (Co(SCN),),- (Ni(SCN),),- (Fe(SCN),)3- or Reinecke salt and extraction into 1,2-dichloroethane. Concentration range 1-2000 vg ml-l investigated using AAS Mossbauer spectroscopy and XRD Knowledge based system for selection of dissolution method for AAS analysis of drugs Study of effect of ethanol on ICP excitation characteristics Review of application of GC-AES to speciation of metals and non-metals in environmental and petroleum samples.Details for Fe Ge Hg Ni Pb Se Sn and V in particular samples tabulated Cr Cu Fe Mn and Ni determined using CaCl as matrix and PdCl as internal standard (ppm Results discussed with regard to pharmacology Elemental profiles of pharmaceutical tablets by ICP- 9313775 Indirect method for determination of cocaine by 9313920 About 100 ancient Chinese mineral drugs LODS; RSDS 5-9%) Various Pharmaceutical tablets MS;ICP;L Various (5) Cocaine AA;F;L Various Chinese mineral drugs AA;F;L 931402 1 941374 941400 941533 Various Drugs Various Ethanol Various (8) Various AA;F;L AE;ICP;L AE;MIP;L AE;a.c.arc;S 941850 Various (5) Trimellitic anhydride Various Chinese herbal drugs Various (12) IBMK AE or AA;ICP or F;L AE;ICP;L 941960 941121 8 LODs for 12 investigated analytical lines for elements in IBMK found to be 2 to 16 fold better with 50% air-Ar ICP cooling gas than with Ar alone as coolant Toxic elements found to be less than LODs for most samples (LODs 2 0.25 1 5 and 10 ppm for As Cd Cr Pb and Sn respectively) EDXRF with optical spectrometry (AAS or DCP- AES or ICP-AES) The product of b.p.(“C) and relative density is proposed as an empirical parameter to decide whether a solvent is suitable for ICP-AES determinations. It is suggested that solvents with products above 70 should be suitable Study of effect of adding various amounts of acetone ethanol ethylene glycol glycerol and 1 ,4-dioxane on FAAS and ICP-AES signal intensities determination of Ba Ca Fe S and Zn in hydrocarbons using WD-XRF. Aqueous standards used for calibration Theory for mechanism of ethanol effect in ICP-AES described mathematically using Einstein- Boltzmann-Saha and Raout-Clausius-Clapyron equations Methodology presented for speciation of Ca Co Cr Cu Fe K Mg Mn Ni and Zn in traditional Chinese medicines Description (with examples) of synergistic use of Fundamental parameters method used for Various (5) Edible fats and oils Various Speciality chemicals AA;ETA,L 94/21 19 XRF;-;S or L 94/21 38 Various Organic solvents AE;ICP;L 9412 142 Various (4) Aqueous organic solvents Various (5) Hydrocarbons AA or AE;F or ICPL 9412203 94/23 5 5 XRF;-;L AE;ICP;L AAETA;L Various Ethanol 9412622 Various (10) Chinese medicine 9412624 CATALYSTS - As Vanadium catalyst AA;F;L Sample (0.15 to 0.2 g) heated with 20 ml H,SO diluted to 100 ml and centrifuged.A 5 ml portion was then treated with 10 ml HCl(1 1) and 10 ml of reductant solution and diluted to 50 ml.ASH generated using NaBH elemental analysis within individual particles of cracking catalyst Pd adsorbed on tribenzylamine impregnated resin columns Sample digested with HF and resulting solution diluted to 1-20 pg ml-I Pt for determination using air-acetylene FAAS (LOD = 1 pg m1-l) Method for determination of Pt emissions in exhaust gases from vehicles equipped with catalytic converters SIMS imaging used for phase identification and 9411 159 Ni Cracking catalyst SIMS 9411536 Catalysts y-Al,O based catalyst AA;F;L AAFL 941840 9411014 Pd Pt Pt Exhaust gases MS;ICP;L 9412794JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 333 R Table 2 (continued) Technique; atomization; Element Matrix analyte form* Re y-Al,O based catalyst AA;F;L Sample treatment/comments Reference 9411 0 14 9411361 As for Pt but concentration range 5-100 pg ml-' Pt using N,O-acetylene flame (LOD= 5 pg ml-') Model Rh catalyst prepared on a flat conducting support consisting of A1 oxide on A1 foil.Conversion of Rh precursor into metallic Rh studied using SIMS and monochromatic XPS Ru xanthate complex formed (by holding sample- xanthate solution at 343K for 20 min at pH 5 to 7) and then extracted into solvent for Ru determination using ICP-AES 94/84 As for Ni Distribution of Cr Fe K Li Ni and Mg on fresh and spent internal reforming catalyst (Ni/MgO) from a molten carbonate fuel cell studied using AAS Possible poison elements deposited on the surface of a used S resistant water gas shift reaction catalyst were measured using the above techniques.Loss of K promoter from the surface was also monitored Investigation of concentration distribution of Pd Pt Rh and Ru (possibly originating from automobile exhaust catalysts) in soil near highways microfluorescence system (spatial resolution down to 50 pm) to analysis of automotive catalysts Fabrication and application of an X-ray Rh Alumina model catalyst SIMS and XPS Ru Alumina based catalysts AE;ICP;L v Cracking catalyst Various (6) Reforming catalyst SIMS AA;F;L 9411536 9314026 Various Co/Mo-alumina based catalyst XRF or AE; 1CP;S or L 941529 Various Soil A A;ETAL 9412145 9412470 Various Automotive catalysts XRF;-;S INORGANIC CHEMICALS & ACIDS- A1 Silicon and electronic rade reagents Molecular fluorescence; - S or L 9 Method based on the complexation of the A1 with the dye mordent black 17.The complex solution in 0.2 mmol I-' (5:20) with 1 mol 1-' acetic acid/ sodium acetate solution buffer (pH 4.8) and kept at 40°C for 1 h. LOD 2 ngml-' 0.01 g of the sample is stirred vigorously with 50 ml of H,O. A 1 ml aliquot of the resulting slurry added to hydride cell. LOD = 2.8 ng. Procedure optimized w.r.t acid and NaBH concentration influence of surfactants on the stability of the slurry Ar flow rate and particle size Direct analysis; LOD of 3 pg Cd Comparison of colorimetric and at absorption 0.1-1.0 g of sample digested with HNO (1 1) and method. Solvent extraction using DDC the digest evaporated to dryness. Residue dissolved in 10ml of 10% HCl Indirect method based on formation of AlF molecule in a N20-C2H2 Flame Two preconcentration methods described Comparison of tetraphenylpotassium borate Analysis of nitrogen-phosphorus-potassium HU02P0,.4H,0 intercalated with Li by direct gravimetry and flame photometry formulation reaction with Li to yield substituted lameller solid.Li determined in resultant solid High precision Li isotope method developed for detection of Li+ ion emitted from lithium phosphate as an ion source material by a Re double filament ionisation Indirect method for iodide based on the formation of a chelated copper complex and extraction of the complex and determination of Cu. LOD= 47 ng ml- The effect of carbon black (l%)on the direct atomization of Mo compounds (dispersed in H,O) was investigated Ni preconcentration by extraction with 5-nitrosalicylaldeh yde-4-phen yl-3- thiosemicarbazone; LOD = 0.2 pg P extracted as phosphoantimonyl molybdate complex into IBMK and Mo determined 941264 AA;HG,S As Fly ash 941169 94/33 94/2 1 02 A AETA;L AA;F;L Cd c u Orthophosphoric acid Copper leachings from anti- fouling coatings Molybdenum concentrates and powder c u AAF;L 94 ,f 1240 Fluoride Toothpaste Molecular absorption;F;L AE;-;S AE;F;L 9411 11 9411770 941388 Lead salts Mixed fertilizers K Complex fertilizer AA:F:L 94 f946 9411 56 Li Protonic solid electrolyte AA;F;S Li MS-iS 9411467 I Laboratory reagents/ commercial grade salts AAF;L 9418 18 941499 9314079 941493 Mo Ni P Molybdenite A A;ETA L AA;F;L AE1CP;L Sea water Brine334R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 Table 2 (continued) Technique; atomization; analyte form* AA;HGL Reference 941494 Element Pb S S Se Sr Sn Sn Te Ti V Various (18) Various Various Various Various Various Various Various Various (10) Various Various ( 17) Various Various Matrix Iron oxide pigments Sample treatment/comments Two sample preparation method employed; 1.ground sample was dissolved in concentrated HCl- HNO (3 1) and on cooling the sample was diluted in 1 mol 1-' HCl and treated with 35% (NH,),S208 and reducing agent (4% NaBH,) was introduced to the reaction cell; 2. Sample was suspended in H,O-0.01 YO sodium hexamethylphosphate and an aliquot of the resulting solution treated with 7 ml HNO,-35% (NH,),S,O,-10% NaBH as above. LOD of 0.81 and 0.2 pg 8-l for acid dissolution and slurry procedure respectively Preparation of S followed by generation of H,S; LOD =0.4 ng ml-I 1-10 nl of sample spiked with 1 pg ml-' Y internal standard+ 100 pg ml-' U placed onto high purity silicon; dynamic SIMS then performed on solid residue. LOD = 4 ng ml - ' Comparison of ion chromatography and ICP-AES Double ion exchange used for separation Tungsten atomizer and palladium matrix modifier employed 0.5 ml of sample solution + 5 ml of 0.1% ascorbic acid applied to a column packed with GXD-301 beads (treated with TBP).The analyte was eluted using HNO and a 10 p1 aliquot analysed 1 g sample digested with 10 ml HC1-HNO (1 3). Te La 1 line and Sc Ka (internal standard) were employed for the analysis ng in HCHO medium. Details of optimized procedures for extraction and instrumental parameters reported final products obtained during multi-stage Ge purification process Samples digested by concentrated acids including HF HClO and HN03 Pd acetate employed as modifier.The LOD was 0.66 V separated by monothio-B-diketo liquid exchanger Procedure for the determination of intermediate and - Sc employed as internal standard. Problems with nebulization avoided by the addition of KOH A comparison of ICP-AES GFAAS XRF & NAA A review with 20 refs AE;ICP:L SIMS 941209 1 9313700 Ultra pure hydrochloric acid Coal fly ash Brine Saline water AE:ICP;L A A;ETA; L A A;ETA;L MS;-;L 94/92 9411390 94/13 Ferric chloride 941152 Selenium WDXRF-;L 9412558 AA;ETA;L AA;ETA;L Coal fly ash Coal fly ash 9313466 9313464 High purity germanium compounds Fly ash Natural gas brines Alkali silicate solutions Coal fly ash Boiler water Hazardous metal wastes AA:ETA;L 931341 1 AA;F;L AE;ICP;L AE;ICP;L 9313420 9313500 9313 5 5 3 9313899 9313982 - AA or AE;F or 1CP;L XRF;-;S Field portable XRF analyser incorporating Hg12 detector employed for rapid screening.Fundamental parameter approach used to eliminate the requirement for site specific standards A review (20 refs) on batch and continuous hydride generation systems High pressure nebulizer employed. Factor 2-8 improvement in sensitivity reduced matrix interferences Samples ignited and dissolved in HCl-HNO 9412 Wastewater High concentration solutions AA;HGL AA;F;L 941143 941270 Ferrous fumarate AA,or AEF or 1CP;L AE;ICP;L 941467 941476 941773 9411012 Ultrasonic nebulizer employed.Effect of LiBO and Analyte preconcentration on amberlite XAD & resin NaCl studied Manganese and nickel compounds Sodium metal AA,F;L AA;ETA;L The sample was converted to NaOH in a desiccator by action of room temp water vapour generated under reduced pressure; nickel nitrate modifier employed. 0.5 g of sample evaporated with HN0,-HCl (1 3) Moist residue boiled with concentrated HCl. Resulting solution mixed with 1 mol 1-' Ca(N03) + Zr + Na2HP0 pH adjusted to 6.5 with aqueous NH precipitate filtered and dried at 600 "C. precipitate ground with ethanol and placed in XRF cell Various Lead concentrates XRF;-;S 9411 0 15JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 335R Table 2 (continued) Technique; atomization; analyte form* Element Matrix Various (4) Cooking salt Sample treatment/comments Reference AA;F;L 4 g of sample dissolved in H20. Resulting solution extracted with 1,1 -dimethylethan- 1-01-2% diethydithiocarbarmate; the organic phase was separated and the organic matter destroyed using 9% HNO,.The residue was then dissolved in 50% HNO 9411 167 MS;ICP;L Sample preparation procedures described Various (34) High purity hydrofluoric acid Various ( 5 ) Chromate slags 9411 191 XRF;-;S Dried sample ground to 200 mesh and 2 g of the sample ground with 2 g of H3BO3 and pressed into a disc described; 13 samples h-l with enrichment factors of x 60 reported A A;ETA;L Fully automated FIA preconcentration system AA;F;L Samples dissolved in HF-HCIO 9411225 Various High purity reagents 9411636 Various Sodium-potassium water glass Various (15) Ultrapure arsenic Various (6) Coal coal fly ash Various Brines Various Antimony Oxide 9411695 AA;ETAL AA:HG or ETAL AA;ETA;L XRF;-;S LODs in range 10-50 ng g-' Decomposition reaction with HNO studied H202-H3P04 modifier employed Press moulding of As203 with 2-10% wt binder.As in 9412092 Zn matrix removed by extraction using 2 mol I-' Analytes extracted by mixture of Na DDC with Samples digested by wet ashing with a mixture of Pressure of press is 2-10 tonne press time 10-30 s NH4Cl and ammonium citrate solution cupferron in MeCOCH2CHMe2 acids under microwave heating. Good agreement with reference material data reported A review of a commercial package for cement plant process control Comparison of pressed powder and borate fusion sample preparation 9411674 9411756 941208 1 9412092 Various Bismuth oxide Various Zinc fertilizer XRF;-S AA;F;L 9412093 9412127 Various Potassium carbonates AA;F;L 9412 154 9412158 Various Fly ash AE;ICP;L Various Cement XRF;-:S 9412426 9412479 Various Samples from a Pb smelter XRFt ;L NUCLEAR MATERIALS- LOD of 160fg Isotope shifts of several Pu isotopes measured for Sample mixed with H3BO3.Rb content determined Addition of known amount of Ba for indirect - several excitation schemes. from U Rb ratio determination of sulfate by analysing for excess Ba. Interference studies reported Various separation methods employed to remove Rb to prevent spectral interference Sample was acidified with concentrated HN03 and 2,2,4-trimethylpentyl hydrogen methylphosphonate.After mixing (15 min) Fe(N0)3 was added and the precipitate with absorbed U is filtered off and pressed into a filter. LOD=0.06 pg 1-' Analysis carried out using thermal lensing spectrometry; LOD = 0.005 mol 1- ' 9411338 9411413 9412668 237Np - Pu Mixed oxide fuel pins Pu - 9412699 Rb Rubidium uranium sulphate XRF;-;L S (indirect) Iron chloride AEICPL 94f754 9412792 99Tc Rubidium MS;ICPL U Water XRF;-;L 9412 17 Nitric acid Laser thermal lens 9415 16 U 9 313 76 8 9412822 U U Irradiated fuels Uranium oxides Description of two robotics systems for sample presentation. A review (9 refs) of methods for the isolation and detection of transuranic elements Kalman filter employed for data processing; no chemical separation of analytes was required Recovery of impurity elements was 95-109% Decomposition of 0.1 g of powdered glass with HF-HClO 94/109 Transuranic elements Various Various Various AE;ICP;L Uranium 9313921 Lithium hydroxide Radioactive waste glass AE;ICP;L AE;ICP;L 94/2 13 9417 18 Various Various (6) Various Nuclear grade uranium Various compounds XRF;-:S 9412272 Various Various A review (88 refs) surveying non-radiometric methods for the determination of long lived radionuclides U separated from U02F2 using tributyl extraction; end on viewing of the plasma Description of ICP-MS instrument situated in a glove box - 9412696 9411 65 1 Various Uranium hexafluoride AE;ICP;L MS:ICPL Various Nuclear materials 9412843 AE;-:S or L 9413538 Various Uranium oxide336R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 degradation products using chromatographic systems coupled to element specific detectors based on atomic spectrometry. The interest stems primarily from growing concerns regarding the effect of fuels on the environment. As in previous years determination of alkyllead compounds both in fuels themselves and in environmental samples continues to attract attention. Determination of total lead in gasoline samples is relatively straightforward with methods usually involving breaking up the alkyllead compounds with halogen prior to determination using atomic spectrometry but a few variations continue to be reported (e.g. 93/3400,93/3406). For environmental samples however determination of total lead concentration alone is rarely sufficient since the trialkyllead degradation products of tetraalkyllead compounds are some 10-100 times more toxic than the dialkyl or inorganic lead compounds.Perhaps the most commonly applied technique for speciation of alkyllead compounds in environmental samples is GC-AAS and two reviews have been published covering this application (93/3642 93/3988). The GC techniques do however suffer from one major drawback in that the trialkyl and dialkyl lead com- pounds are relatively involatile necessitating time consuming derivatization procedures prior to analysis. Separations based on reversed-phase liquid chromatography can also be used for determination of alkyllead compounds and have the advantage that both volatile and involatile (including inorganic) species can be determined.In order to achieve comparable limits of detection however sensitive detectors (e.g. ICP-MS) must be used. Epier et al. (94/2394) have described the use of LEI as a detector for speciation of organolead compounds using liquid chromatography and reported detection limits comparable with those which can be achieved using ICP-MS (sub ng ml-l). The environmental impact of fuel combustion products is substantially influenced by oxygen and sulfur compounds contained in the fuels. Quimby et al. (94/436) have described how GC-AES can be used to carry out fast (< 10 min) analysis of these compounds in gasoline. Response factors were found to be largely independent of compound type allowing easy calibration with external standards. A similar approach has been used to study the effects of catalyst type and process conditions on the distribution of sulfur compounds in FCC gasolines (94/135).Some problems often encountered with commercial GC-AES systems however are intolerance to solvents and wall reactions in the capillary discharge tubes (necessitating solvent venting and addition of reagent gases). Goode and Thomas (94/2393) have shown that by using a tangential $ow torch it was possible to determine oxygen containing additives in gasoline by GC-MIP-AES without solvent venting or use of reagent gases. Using on-line helium purification LODs were reported to be 1 ng s-' and selectivity over carbon was found to be 4850 1 when the plasma was viewed laterally (c.J 155 1 for axial viewing). GC-AES has also been used for determination of organo-arsenic compounds in natural gas (94/C1954).Several forms of arsenic were detected including t rimet hylarsine dime th ylethylarsine,and diethylmethylarsine. The ability of GC-AES to provide simul- taneous multi-element chromatograms is a feature which has not as yet been widely exploited. Kosman (94/131) has shown that the additional information provided by element specific simulated distillation can provide enhanced discrimination compared with conventional univariate GC for fingerprinting of petroleum products. Furthermore application of principal component analysis to data from a set of highly evaporated fuels was found to give distinct clusters for each fuel regardless of the degree of evaporation providing a potentially powerful method for tracing the source of environmental spillage samples.Although not strictly atomic spectrometry readers may also be interested in a report of a pulsed discharge photo- ionization detector (PDPTD) in which the atomic lines of argon were used to provide selective ionization of analytes (94/C1955). Analytes such as hydrocarbons aldehydes amines and sulfur and halogen compounds were selectively ionized compared with nitrogen oxygen water and carbon dioxide making the technique particularly suitable for measurement of air pollutants. Unfortunately some important compounds (e.g. methane sulfur dioxide and C1 fluorinated compounds) could not be detected. Among the other papers published during the review period readers may be interested in a method (93/3362) for determi- nation of Ni and Vin gasoline by ICP-MS with micro-emulsion sample introduction (LODs 10 and 20 ng ml- ' respectively) and a report on the use of TXRF for differentiation between pure fuel oil (bunker oil) and waste oil (sludge) in maritime shipping legal cases (94/656). In addition the method proposed by Curtius et al.for stabilization of metals in kerosene as a three component solution (discussed in last year's ASU (93/3400)) has now been published (94/586). The three compo- nent solution which comprised propanol/kerosene/0.2% nitric acid (> 11 5 2) was found to be stable with respect to Cu and Pb concentration for at least 3 h in an autosampler cup and for at least 24 h in a closed flask. 2.1.3. Lubricating oils During the current review period there has been a dramatic reduction in papers published concerning determination of wear metals in lubricating oils.The few exceptions were reports of the use of ICP-AES (94/1730) TXRF (94/2482) and FAAS (94/2711) for this application. Users of the latter technique may be interested in a new fluorinated high density polyethyl- ene spray chamber which is claimed to give reduced carbon deposition on the burner head and requires less acetylene than conventional spray chambers for analysis of oils using FAAS (94/1100). Of more interest perhaps is the report concerning determination of wear metals originating from ceramic engine components using ETV-ICP-MS (94/C1991). These materials are increasingly being used as replacements for steel in compo- nents where hardness and resistance to high temperatures and corrosion are important characteristics (e.g.ball bearings) and so methods for monitoring their performance (and perhaps preventing catastrophic failure) are required. In the application reported the authors used the metals Al Mg and Y to monitor wear from silicon nitride ball bearings with the ETV allowing separation of the analytes from interfering species arising from the hydrocarbon matrix (e.g. C,). Waste oils are potentially extremely hazardous materials which can contain a number of compounds universally accepted as toxic or environmentally unfriendly (e.g. heavy metals PCBs). Generally methods are reasonably well estab- lished for analysis of these materials. However two papers may be of interest. The first is a report of use of isotope dilution GDMS for determination of lead in waste oil (94/2395).The method which involved mixing an isotopically spiked aqueous leachate with a conducting host matrix and then pressing this into a GD cathode was stated to be the first step toward the long term goal of direct analysis of oils by isotope dilution GDMS. The second application was a method (94/278) for difeerentiation between organic (e.g. PCBs) and inorganic chlor- ine in waste oils using ETV-ICP-MS (see also J . Anal. At. Spectrom. 1993 8 337R). The differentiation is achieved using ETV temperature programming having one step at 400 "C for vaporization of the PCBs and a second at 2650 "C for vaporiz- ation of the inorganic chlorine compounds. The detection limits were between 0.5 and 10 pg PCB g-' oil depending on the nature of the oil and the degree of chlorination of the PCB.The method provided a means for rapid screening of oils to produce an upper limit for PCB concentration with those above a specific threshold being subjected to the more rigorous (and time consuming) analysis using GC-ECD or GC-MS. 2.2. Organic Chemicals and Solvents This section of the review covers the analysis of organic chemicals and solvents and the format is essentially the sameJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 337R as that of previous years (see J. Anal. At. Spectrom. 1993 8 337R). A summary of the work concerned with the analysis of organic compounds and solvents carried out during the period under review is provided in Table 2.2.2.1. Chemicals This year has seen something of a renaissance in the use of atomic spectroscopy (particularly AAS) for indirect determi- nation of molecular compounds particularly for pharmaceut- ical applications. The methods most commonly employ reaction with a metallic compound (e.g. formation of an ion pair) subsequent precipitation or extraction into an organic solvent and measurement of the resulting metal concentration using AAS. An example of the former approach which has been reported is a continuous precipitation system for the indirect determination of reducing sugars in wine based on the classical reaction with Fehling's solution (94/703). The reagent was injected directly into the wine carrier (continuously aspir- ated into the AAS instrument) causing precipitation of copper oxide.The reduction in the signal measured at 324.7 nm gave a measure of the concentration of reducing sugars in the wine (range 10-1 10 pg/ml). No sample pre-treatment was required. A similar approach has been reported for determination of the alkaloids papaverine strychnine and cocaine by continuous precipitation with Dragendorff 's reagent (94/2204). The precip- itating reagent ( Bi14- complex) was injected into the carrier stream containing the alkaloid and the precipitate formed was retained on a removable stainless-steel filter. The drugs could be determined in the ranges 1.5-18 4-60 and 6-100 pg ml-' for papaverine strychnine and cocaine respectively at a rate up to 100 samples h-'. Previous work by the same authors had shown that for determination of cocaine Dragendorff's reagent gave the highest sensitivity when compared with other metal complex anions although it was found that [ Fe( SCN)6]3- was the most selective (93/3920).Several indirect methods have also been reported which utilize extrac- tion of the analyte/metal complex into organic solvent rather than precipitation. Examples include an indirect method for determination of cocaine hydrochloride by extraction of the ion pair formed with Co(SCN) into chloroform (94/151) indirect AAS determination of cationic surfactants in waste effluents and shampoos by formation of ion pairs with hexanitrocobaltate(II1) and extraction into dichloroethane (94/344) determination of free fatty acid (FFA) in organism samples by formation of Cu-FFA soaps (94/1755) and indirect determination of tetradecylpyridinium bromide by formation of an association with (CdBr4)2 - and extraction into dimethyl- benzene (93/353 1).Concentration ranges for these methods are typically in the range 0.1-tens ofppm but obviously interferences can be a problem if there are concomitant metals/ compounds in the sample which can also form ion pairs with the complexing agents. A rather unusual indirect AAS method has been reported by Jin et al. (94/230) for determination of arginine using GFAAS. The method is based on preconcen- tration of Cu" on a Nafion 11 7 (Du Pont) coated tungsten coil and then measurement of the amount of copper deposited on the coil by placing it in the graphite cup of a Zeeman AAS instrument. Exchange of the analyte with Cu" caused less copper to be deposited on to the membrane and so differences in Cu signal obtained when the experiment was performed with and without the analyte solution allowed arginine to be determined in the range 31-250 nmol 1-I. In the determination of 130 nmol I-' arginine the authors reported no interference from 2 pmol 1-l cephradine 15 pmol 1-1 ammonium oxalate urea glucose salicylic acid citric acid D-tyrosine thiourea or 31 pnol 1-1 tartaric acid.The method has also been applied to the determination of the anti-cancer drug nitrocaphamum in the range 1.1-11 pmol I-' (94/2800) although aniline was found to cause significant interference in this case. Preconcentration on a Nafion modified metal coil is also amongst the plethora of methods which have recently been reported for direct determination of metals in pharmaceutical products (93/3575).In this particular study Bi in drugs in the range 1-30 ng ml-' was determined using graphite furnace AAS (with apparently no interferences from other metals or organic substances). Atomic absorption spectrometry has also been used for determination of Cr Mo and Se in total paternal nutrition solutions (94/1710) whilst the rapid multi-element capability and sensitivity ICP-MS has been shown to provide an extremely effective method for obtaining elemental profiles of commercially available health aids (93/3775). Although Hg was among the elements detected in the latter profiling work ICP-MS is not an ideal technique for quantification of this element due to the tendency of mercury to 'stick' in the sample introduction system.A better approach for this element may be cold vupour AAS as utilized for determination of mercury from medicines dissolved in synthetic stomach solutions (94/353). The presence of trace elements in traditional Chinese medicines and their role in the pharmacology of the drugs is an area which appears to be attracting increasing interest (93/4021 94/960). In addition to multi-element approaches based on ICP spectrometry ETAAS (93/4021 94/2624 94/2801) and determination of Hg using CVAAS (94/2624 and 94/2801) have also been used for this application. It is however apparent that in order to gain a full understanding of the role of metals in the pharmacology of the drugs it is necessary to obtain some information regarding chemical speciation in addition to total element concentrations.It has been shown that this is best achieved by utilizing atomic spectrometry along with other analytical techniques such as Moessbauer spectroscopy and X-ray difiraction (93/4021) or HPLC polar- ography and spectrophotometry (94/2624). Readers may also be interested in a knowledge based system for selection of dissolution methods for analysis of drugs using AAS (94/374). The use of GC-AESfor chemical speciation of elements in chemical products continues to attract attention although there is some evidence that the rate of publication of new applications is slowing down from the heyday which followed the introduction of robust commercial instrumentation a few years ago.In addition to the applications for analysis of petroleum and petroleum products (discussed in Section 2.1 ) the technique has also been widely applied for analysis of chemicals in general. Recent advances have been reviewed by Lobinski and Adams (94/533) and details of the speciation of Fe Ge Hg Ni Pb Se Sn and V were tabulated. A general discussion of the application of GC-AES to a wide variety of compounds has also been published (93/3610) and new 'recipes' (selective detection schemes) for use with the software of a computer controlled system for selective detection of Al B Cr Ga Mn Pd Pt Rh Ti and V presented. GC-AES has been used together with HPLC to study diastereoisomerism of oxovanadium N,N'-propylene-bis ( trifluoroacetyl-acetonimin- ate) and other Schiff base chelates of Cu Ni and Pd.The pigogramme detection limits of GC-AES facilitated the study of kinetic behaviour at low concentrations. The capa- bility of GC-AES to provide element specific detection for both metal and non-metal elements also aided identification of the eluted peaks. In many simpler cases however this may not be necessary and so a simpler approach e.g. based on GC-AAS will often suffice. Forsyth et al. (94/756) have used this approach for determination of organotin compounds in edible oils. In this method analyte compounds were extracted using 0.05% tropolene in 0.04 mol 1-' hydrochloric acid- methanol and the extracts were cooled in dry ice-methanol to remove approximately 64% of the non-volatile co-extractives. Since the alkyltin compounds are relatively non-volatile methylation with Grignard reagent was necessary in order to obtain satisfactory gas chromatograms.This time consuming step can be obviated by using SFC rather than GC for non- volatile compounds. Vela and Caruso (94/2294) have compared SFC-ICP-MS with SFC-FID for determination of organotin338 R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 compounds using an SB-Biphenyl-30 column with carbon dioxide mobile phase (see also J. Anal. At. Spectrom. 1993 8 337R). Limits of detection using SFC-ICP-MS were 0.26,0.80 0.57 and 0.20 pg for tetrabutyltin tributyltin chloride tri- phenyltin chloride and tetraphenyltin respectively i.e. more than an order of magnitude better than SFC-FID. The determination of volatile chlorinated compounds in air is important both for occupational health and environmental applications.A new Jibre-optic spectrochemical emissions sensor (‘HaloSnif’) has been described which could provide a con- venient means of monitoring these compounds (94/2130). The system comprises a 50 pm diameter inlet capillary r.f. excited He plasma fibre-optic cable and a measuring system in which the Cl emission line is optically filtered and measured. The limit of detection for trichloroethylene in air was reported to be 1 ppm with a linear range of over four orders. The system is compact and robust and has been successfully tested at several waste remediation sites. Although not strictly atomic spectrometry a method has also been described for determi- nation of organic chlorine using a graphite furnace AAS instrument (94/1137).The authors used the lead atomic line at 261.417nm to measure the AgCl molecular absorption produced when the C1-containing compounds were heated in a graphite furnace in the presence of silver nitrate. 2.2.2. Solvents In previous years many workers have reported on the effects of organic solvents on ICP-AES emission intensities (see e.g. J. Anal. At. Spectrom. 1993 8 337R). The suitability of a particular solvent for use with ICP-AES depends primarily on its physical properties (e.g. density surface tension viscosity) with the heavier less volatile solvents generally exhibiting fewer problems. Matsunaga (94/2142) has suggested using the product of the boiling point (Centigrade) and the relative density as an empirical parameter for assessing the suitability of a solvent for use with ICP-AES.Solvents whose parameter was greater than 70 were reported to be suitable (except for dioxane). Todorovic et al. (94/2203) have studied the effect of aqueous organic solvents with different physical characteristics on the determination of trace elements (Ca Cd Cu and Fe) by FAAS and ICP-AES. Three volatile solvents (acetone ethanol and 1,4-dioxane) and two less volatile solvents were used in the investigation. Addition of the volatile solvents was found to give a significant enhancement for all of the element lines studied whereas addition of the less volatile solvents generally gave suppressions. Several other workers have also studied the influence of ethanol on ICP-AES line intensities. Yang et al.(94/400) have found that for high excitation potential atomic lines intensities continuously decreased with increasing ethanol concentrations but for low excitation poten- tial lines the intensities reached a minimum at 20% ethanol with the magnitude of the effect directly proportional to the excitation potential of the line. It has been claimed that the effect of ethanol in ICP-AES can be explained with the help of a mathematical model based on the Einstein-Boltzman-Saha and Raout-Clausius-Clapeyron equations (94/2622). However it is clear from the apparently contradictory reports described above that the effects observed are very dependent on the experimental conditions used. It has been shown for example that the auxiliary gas flow rate can substantially influence the distribution of the solvent loading in the plasma sample injection channel causing changes in excitation tem- peratures and height emission profiles (93/3390).The C emission signals were found to give the clearest indication of organic solvent-plasma interactions. The use of an air-argon plasma for analysis of samples dissolved in IBMK has been described by Tang et al. (94,4218) (see also J. Anal. At. Spectrorn. 1993 8 337R). Signal-to-background ratios were found to be optimal for atom lines with 50% air added to the plasma cooling gas while ion lines were best with 10% air. As with previous work LODs were claimed to be substantially better (2-16 fold) than with an all argon plasma. Solvent extraction is widely used within industrial labora- tories for the analysis of difficult matrices affording a means of preconcentrating analytes reducing dissolved solids concen- trations and eliminating matrix interferences.However the exact composition of the matrix solution (pH ionic strength etc.) and solvent used can have a major influence on the distribution properties of the extractants. Dissociation con- stants dimerization constants and partition coefficients have been determined for two commercial extractants (D2EHPA and Versatic acid 10) for extraction into benzene and kerosene from solutions at various pH and ionic strength (94/473). The data presented will be valuable for anyone contemplating use of either of these reagents for solvent extraction. 2.2.3. Catalysts As discussed in previous Atomic Spectrometry Updates (see J.Anal. At. Spectrom. 1993 8 337R) methods for determi- nation of the concentration of active metals (usually PGMs) in catalysts are fairly well established. However elemental analysis of catalysts based on y-alumina can be problematic in view of the difficulty in dissolving this matrix. Readers may therefore be interested in a method which has been developed for determination of Pt and Re in deactivated catalysts based on y-alumina (94/1014). Samples were digested in hydrofluoric acid and Pt and Re determined using FAAS. In some cases it may be advantageous to preconcentrate the active metal and/or separate it from interfering matrix components prior to measurement using atomic spectrometry. However this is not always easy to achieve for the platinum group elements.Watanabe et al. (94/84) have used potassium xanthates to extract Ru into organic solvent for analysis of alumina-based Ru catalysts using ICP-AES. The complete formation of the ruthenium xanthate complex in this case required holding in a water bath at 343 K for more than 20 min at pH 5-7. Immobilization of the chelating agent on a solid support is generally a more convenient approach than solvent extraction for preconcentrating analytes and separating from matrix components. This approach has been adopted by Tang et al. (94,4340) for determination of Pd in catalyst samples. The columns were prepared by impregnating 1300-11 resin with tribenzylamine and column conditions for adsorption of Pd were investigated using FAAS.Premature failure of process catalysts can very often be due to poisoning from trace contaminants in the feedstocks which can become concentrated on the catalyst surface. Since it is not always obvious what the poisons may be rapid multi- element techniques are generally most appropriate. Thus XRF and ICP-AES have been used to measure elemental contami- nants in a cobalt-molybdenum/alumina sulfur resistant catalyst which had been used for 6 months in a water gas shift reactor (94/529). It was found that the low temperature activity decrease of the catalyst was mainly due to adsorbed poisons from the feedstocks and partial loss of potassium promoter. Although somewhat less suitable in view of its lack of multi- element capability AAS can also be used for measurement of elemental poisons on catalysts if the elements of interest can be pre-selected on the basis of past experience.Cavellero et al. (93/4026) have used AAS to study the distribution of Cry Fe K Li Mg and Ni on fresh and spent reforming catalyst (nickel/ magnesium oxide) from a molten carbonate fuel cell. In this case however optical observations and porosimetry analysis showed that a thin glassy layer of KOH on the external surface of the catalyst was the most likely cause of deactivation. AAS or AFS with HG is also a powerful tool for investigation of catalyst poisoning in view of the extremely low limits of detection which can be achieved using this technique. An example of this approach is the determination of As in vanadium catalyst using HG and atomic fluorimetry (94/1159).JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 339R For some complex catalysts (e.g. FCC) the catalyst pellets comprise a composite of particles of differing matrix (e.g. rare earth exchanged zeolite binder metals trap). In these cases it is important to determine not just the total concentration of metal poisons on the catalyst but also how they are distributed amongst the different types of catalyst particle. Scanning SIMS with image processing has been shown to be one of the most powerful analytical techniques for this type of application (94/1536). SIMS can also be used to great effect in studying the conversion of catalyst metals from precursors into their active forms. Borg et al. (94/1361) have used static SIMS along with monochromatic photoelectron spectroscopy to study the preparation of a rhodium catalyst from rhodium trichloride on a flat conducting alumina support.The control of vehicle exhaust emissions using PGE-loaded catalysts is now well established in many countries throughout the world. However there is now growing concern that the PGGs in these catalysts can get into the environment through mechanical and chemical attrition and may ultimately rep- resent an environmental hazard in their own right. A method has been presented for determination of Pt emissions in exhaust gases using ICP-MS (94/2794) while graphite furnace AAS has been used to measure concentrations and distributions of PGEs in soils around the A66 Frankfurt-Wiesbaden highway (94/2145). In the latter study average abundances of 10 and 3 ppb were found for Pt and Ru respectively in 71 near surface soils taken from around the highway.Only the uppermost soil layer (down to 20cm) contained measurable PGE concen- trations indicating anthropogenic origin. The PGE concen- trations were also found to decrease with increasing distance from the highway providing further evidence that the source is most likely automotive catalyst emissions. 2.3. Inorganic Chemicals and Acids The requirement to analyse materials with high dissolved solid content continues to pose a challenge for analytical chemists as evidenced by the variety of abstracts received on the subject in the current review period. The drive towards faster cleaner direct methods involving minimal sample pre-treatment has largely been addressed by two approaches either improvements in sample introduction or by the use of inventive front-end matrix-analyte separations which lend themselves to some form of automation.An automated system based on ion exchange for the separation of trace constitutents in pure alkali metal salts has been decribed (94/569). In this application the separation procedure served the dual function of preconcen- tration of analyte while at the same time providing a means of matrix elimination. On elution from the ion exchange column the analytes were determined on-line by sequential ICP-AES. The optimal flow rates for both the chromatography and ICP were determined. Elution kinetics and dispersion of trace analytes were studied for both standards and for alkali metal salt solutions.This approach allowed direct on-line analysis. A similar approach was reported for the determination of trace metals in concentrated brines using ICP-MS (94/2182). Alkaline earth and first row transition elements were isolated from the brine matrix using chelating ion-exchange columns. Two types of column systems were evaluated a commercially available resin and an in-house dynamically-coated chelating- exchange resin. The method was also applied to the analysis of reference materials (NASS-3 Open Ocean Seawater). Linear calibrations were reported in the concentration range of inter- est (<200 pg 1-l) and good agreement with certified values obtained. Flow injection ICP-MS has been employed for the analysis of high purity nickel (94,' 614).The influence of the nickel concentration on the detection limits and matrix inter- ferences were investigated. An interpretation of the large differences in matrix effects found for different elements was also presented. The use of microsampling flow injection for the analysis of high dissolved salt samples has been described (93/3389). Flow injection parameters such as sample delivery rate and sample loop volume were optimized for peak height signals. Detection limits in a 3% m/v sodium chloride solution were reported to be improved by a factor of 2-5 over continu- ous nebulization. Recoveries from spiked sodium chloride solutions were in the range 83-119%. Extraction/preconcentration procedures were prevalent amongst this years abstracts.A double ion exchange procedure has been employed for the determination of Sr in brine water samples by mass spectrometry (94/1390). Nickel has been determined in sea water and common salt by FAAS following an extraction procedure using 5-nitrosalicylaldehyde- 4-phenyl-3-thiosemicarbazone (93/4079). Two separation methods for the extraction of Hg from salts have been proposed (94/1770). The first involved the preconcentration of Hg follow- ing introduction of lead sulfide whilst the second involved coprecipitation of Hg after partial decomposition of the matrix with ammonium sulfide or sodium sulfide. The lead sulfide precipitate containing the Hg was analysed by AES using hollow iron electrodes. Other examples reported included the determination of trace elements in natural gas brines by ICP-AES (93/3500) alkaline earth elements in brine by ETAAS (94/2080) and Li in protonic solid electrolyte by FAAS (94/156).The analysis of high purity materials and reagents continues to require more demanding analytical methodologies. The stringent requirements for ever improving purity levels particu- larly in the semiconductor industry provides a focus for leading edge developments in analytical atomic spectrometry. The analytical sensitivity and elemental coverage provided by ICP-MS has made this technique invaluable in this type of application. A method for the determination of 34 impurity elements in highly purified HF using ICP-MS has been reported. Preparative procedures were described for As Au B Nb and Ta (94/1191).Zeeman-effect AAS has been used for the determination of impurities in intermediate and final product in a multi-stage process for germanium purification (93/3411). The matrix was removed by evaporation without loss of impurities. The optimum operating conditions were the same for germanium tetrachloride germanium dioxide and elemental germanium. Results were presented for 18 impurity elements the lowest detection limits reported were in the order of 1 x 1014-1 x 10l6 atoms cm3. The analysis of ultrapure hydrochloric acid for non volatile residues by microvolume-SIMS has been described (93/3700). 1-10 nl of sample solution spiked with 1 pg ml-' Y internal standard + 100 pg ml-I U stabilizer was deposited on high purity silicon. Static SIMS was then performed on the sample residue.A detection limit of 4 ngml-' for the determination of S was obtained using this procedure. The use of a sealed ICP for the direct determination of impurities in semiconductor grade chlorine gas has also been reported (94/C1885). A number of studies relating to the analysis of acids have been reported. Matrix effects of both potassium chloride and phosphoric acid in ICP-AES have been investigated. (94/2217). It has been shown that low concentrations of both matrices cause significant depressive effects on the relative emission intensities of Fe Mg Mn Sr and Zn under normal analytical conditions. The depression in signal was found to be more pronounced for potassium chloride than phosphoric acid at the same analyte /matrix concentration ratio.The matrix effects can be corrected by increasing the power applied to the plasma which was shown to correlate to the excitation energy of the emission line employed. The effects of low acetic acid concentrations (3-10% m/v) on selected analytical lines have been studied as a function of incident power and carrier gas flow rates (94/2398). Regulatory requirements and the ever increasing demands of environmental monitoring have resulted in a steady increase in the number of abstracts relating to the analysis of materials resulting from power station emissions. A method for the340 R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 characterization of ash deposits using laser spark source emis- sion spectrometry has been described (94/2140).This system was developed for the real-time monitoring of elemental com- position of ash deposits formed during the coal combustion process. Comparison of relative emission intensities of Al Ca and Fe allowed assessment of ash composition. The direct determination of Ag Cd Cu and V in fly ash has been demonstrated using pressure regulated ETAAS (94/2579). The sample was introduced directly into the atomizer and no thermal pre-treatment was required. A small amount of water was deposited on top of the sample to prevent loss of sample during chamber evacuation. Good agreement was obtained with certificate data for NIST coal fly ash SRMs. A comparison of a number of analytical techniques for the analysis of Coal Fly Ash has been described (93/3899). Thus ICP-AES XRF ETAAS and NAA were evaluated and the need to employ SRM’s to ensure the validity of data generated was stressed in all cases.Arsenic was determined in fly ash by FAAS by HG from a slurried sample (94/169). The samples were obtained from a thermal power plant burning lignite. A 0.01 g sample of the ash was stirred vigorously with 50ml of water and a 1 ml aliquot of the resulting slurry transferred to the reaction vessel of the hydride generation set-up. This procedure was optimized in respect of acidity sodium borohydride concen- tration argon flow rate the influence of surfactants on the stability of the slurry and the particle size of the slurry. The particle size of the slurry was found to be the most critical parameter and was required to be <8.5 pm. Using this pro- cedure a detection limit of 80 ng As was obtained.Other methods for fly ash analysis reported during the review period included the determination of heavy metals by ICP-AES (94/2158) Co by ET-AAS using probe atomization As Cd Hg T1 and Zn by ETAAS and HG FAAS (94/1756) Ti by ETAAS (93/3466) and V by ETAAS (93/3464). In addition a comparison of several digestion procedures for fly ash analysis has also been reported (93/3420). Atomic spectrometric techniques continue to be widely applied in the assessment of industrial waste water streams. The determination of nine metals in chromium/nickel plating baths by simultaneous FAAS employing Smith-Hieftje back- ground correction has been reported (94/1851). The use of a portable XRF analyser is described for the rapid screening of hazardous metal wastes.The instrument employs a mercuric iodide energy dispersive spectrometer. Results for the rapid screening of soil samples from a number of different sites were presented. The use of fundamental parameters for calibration purposes was described (94/2). 2.4. Nuclear Materials The ability of ZCP-MS to provide both elemental and isotopic determinations with excellent sensitivity and multi-element coverage make the technique ideally suited to applications within the nuclear industry. A commercially available ICP-MS instrument has been installed in a glove box (94/574,94/2843). The nebulizer plasma torch and interface were located within the glove box and the remainder of the instrument was located outside. The sensitivity of the instrument was reported to be less than that for conventional ICP-MS owing to the incorpor- ation of a flange that separated the mass spectrometer from the vacuum interface.This changed the distance between the skimmer cone and the ion lens system. The plasma torch was mounted in a fixed position and the load coil was 25 mm from the tip of the sampling cone. Optimization of operational parameters signal stability isotopic ratios and levels of oxide and hydroxide polyatomics were evaluated for the modified instrument for the determination of fission products and actinides. The analysis of highly radioactive samples by ICP- MS has been described (94/2859). An HPLC system was interfaced to an ICP-MS for the analysis of heavy jssion products. This system allowed the on-line separation of sample components by ion chromatography and subsequent analysis Despite the emergence of ICP-MS for the analysis of nuclear materials ZCP-AES still dominates the literature and the majority of abstracts received in this review period reflected this.A summary of the relevant applications are summarised in Table2. An end-on viewed ICP has been used for the determination of B Cr Mo Si and Th in uranium hexafluoride (94/1651). An analytical method has been reported for the determination of simulated high level radioactive glass (94/718). The glass samples were fused with sodium peroxide and then analysed by ICP-AES. A study of uranium matrix interference in ICP-AES has been reported (94/630). Fifty-one prominent lines from ten elements (B Cr Mo P Sb Si Ta Ti V and W) were investigated.XRF spectrometry continues to be widely applied in the nuclear industry. Methods reported include the determination of Cd Hf Hg and Gd in uranium solutions (94/1592) determi- nation of uranium in water (94/217) determination of impurit- ies in nuclear grade uranium compounds (94/2272) and measurement of Rb in rubidium uranium sulfate. by ICP-MS. 3. ADVANCED MATERIALS Developments in technique and methodology for the analysis of advanced materials are summarized in this section of the review. A comprehensive listing of all analytical methods reported in the year under review is presented in Table 3. Some of the more important areas where progress has been made are highlighted in the text. 3.1. Polymeric Materials and Composites Perhaps the most noticeable feature of the literature this year has been an upsurge in interest in the determination of heavy metals in polymers and paints.In the latter case the environ- mental hazards associated with lead-based paints has resulted in a number of investigations associated with standards for field monitoring. The American Association for Laboratory Accreditation has developed an Environmental Lead Laboratory Accreditation programme aimed at companies carrying out environmental assessment activities (94/C1907 94/C1909). It was stipulated that laboratory quality systems should encompass the design and execution of sampling analysis field testing and assessment of data for lead-based paint. An environmental lead proficiency programme has been described in which quarterly interlaboratory trials have been conducted using real samples since December 1992 (94/C1910).Around 200 laboratories are now participating but there is still a need for appropriate methods of standardiz- ation and calibration particularly for field work. Standard reference materials (SRM 2580 2581 2582) are now in prep- aration for lead in powdered paint at levels closer to regulatory limits having nominal Pb contents of 0.05 0.5 and 5.0% m/m respectively (94/C1908). Several methods have been published for the determination of Pb in paint in the year under review involving ETAAS with ammonium hydrogen phosphate as a matrix modifier (94/1788) and AAS and ICP-AES using micro- wave digestion (94/997 94/1773). The presence of toxic elements in plastic toys has been a matter of concern for some time and a European Standard has been prepared by a technical committee CEN/TC52 Part 111 ‘Toxicity of Toys’.This standard sets out the maximumJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 341 R Table 3 SUMMARY OF ANALYSES OF ADVANCED MATERIALS Technique; atomization; Element Matrix analyte form* Sample treatment/comments Reference POLYMERIC MATERIALS AND COMPOSITES- A1 Polypropylene AA or AEF or 1CP;L Sample (10 g) was melted in a platinum crucible and evaporated and the residue was heated gently with 0.5 ml HNO four times then evaporated to dryness with 0.5 ml H2S04 and fused with lg of potassium bisulphate before dissolution in dilute H,S04; detection limit by AAS was 1.0 pg/ml and by ICP-AES was 0.16 pg ml-' Depth profiling on an aluminium thin film deposited on polypropylene substrate Direct determination of Ca in the range 30-250 ppm; comparison with potentiometric FIA method International measurement evaluation programme Use of Cd 11 1 enriched spike for certification of four polyethylene reference materials; certified Cd content reported as 40.9 75.9 197.9 and 407 pg g-' respectively Sample was digested under pressure in PTFE bombs and by high pressure ashing with HNO,; interlaboratory laboratory comparison gave mean result of 0.059 pg g-' Solid sampling Zeeman AAS used for homogeneity testing of 4 CRMs containing Cd in the range 40-400 pg g-'; 60 analyses were carried out on each using microsamples in the range 60-250 pg depending on Cd content reported with RSD of 4.8% determination of Cr"'; ion pair HPLC and chelating ion exchange methods were compared with spectrophotometric method Examination of no-rinse pre-paint coatings used in control of corrosion; characterization by FT-IR and Auger spectroscopy Air was sampled using a 37mm PVC membrane filter which was treated with 0.07 mol I - ' cupric acetate to form a Cu-polymer precipitate which was digested with HN03 and HC104 and Cu measured to determine polyacrylate present in air Study of deposition of fluorinated polymer film from r.f.plasmas containing sulfur hexafluoride and benzene Comparison of methods for the determination of Ge using lines at 265.118 and 303.906 nm; detection limits of 13 and 31 ng ml-' reported respectively; matrix matching of standards and samples recommended Measurement of co-monomer content of oxygen containing polymers; RSDs.of 2.7% was reported for 7 measurements of a polymer containing 1.12% 0 Microwave digestion using HN03-HF mixtures; accuracy and repeatability of the recommended procedure were evaluated using NIST SRM 1579 powdered lead based paint HN0,-H202 peroxide with microwave digestion using a mixture of HN0,-HC1 matrix modifier; the ashing temperature for Pb could be increased to 800°C and sensitivity was increased by 50%; recoveries were reported in the range 95-104% with RSDs of 5.5-7.070 of 4.8% IMEP-2 Laser ablation of polymer; LOD of 0.016% m/m Extraction and separation procedure for the Comparison of hot plate digestion of sample in Use of ammonium hydrogen phosphate (4%) as As for Ca; LOD of 0.04% m/m reported with RSD Procedure for the calibration operation and maintenance of XRF spectrometers applied to the determination of silicone coatweight on release liners used in the pressure sensitive adhesive industry 941225 1 A1 Polypropylene Ca Paper machine water Cd Polyethylene Cd Pol ye th ylene XPS and SIMS AE;DCP;L IDMS IDMS 9412 7 84 9313379 9313447 9313583 AA ETA;L 94/37 Cd Paper Cd Polyethylene AA;ETA;S 941163 1 Ca Cr Poly(viny1 chloride) AE;laser;S Leather AA:ETA or F;L 9412392 941127 941158 941779 Cr Acrylic copolymer coatings AE;ICPL Polyacrylate AE;ICP;L c u (indirect) 9313766 9411718 F Ge Polymer film AE;plasma;S Poly(ethy1ene terephthalate) AE;ICP;L 0 Co-pol ymers XRF;-;S 941235 1 Pb Paint AE;ICP;L 941997 941 177 3 9411788 Pb Pb Paint Paint AA or AE;F or 1CP;L AA;ETA;S AE;laser;S XRF;-:S 9412392 9412324 Sb Si Poly(viny1 chloride) Silicone342 R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 Table 3 (continued) Element Matrix Technique; atomization; analyte form* Sample treatmentlcomments Reference Sn Poly(viny1 chloride) AAHG;L Sample (0.5 g) was dissolved in DMF treated with 9412249 5 ml saturated bromine solution in carbon tetrachloride warmed till colourless and repeated; after cooling and dilution with DMF it was mixed with 3 ml 1.7% sulfuric acid in DMF and 2 ml of formamide in the hydride generator and after passing nitrogen through the vessel for 30 s 4 ml of 3% sodium tetrahydraborate in DMF was added ,4s for Al; detection limit by AAS was 0.9 pg ml-’ and by ICP-AES was 0.04 pg ml-’ Samples were applied to glass slides dried and removed by softening with solvent prior to direct analysis using energy dispersive instrument; detection of Ca C1 Co Cr Cu Fe K Mn Ni P S Ti and Zn for forensic purposes Direct introduction of wax melted at 122 “C using a Babington V-groove nebulizer and a spray chamber heated at 21 5 “C; rectilinear calibration achieved up to 10 ppm for Al Cd Cu Fe K Na and V; detection limits at or below lppm reported Sample decomposition using NaOH and NaNO,; As Ba Cd Cr Hg Pb and Sb were precipitated from solution using ammonia solution with NaDDC; the precipitates were collected on filters and examined directly by XRF using hydraulic high pressure nebulization for detection of Cd Co Cu Fe and Ni Identification of paper from different manufacturing processes by energy dispersive analysis Fundamental parameter method applied to examination of films < 10 pm thick for analytes at concentrations of 1 pg cm-’ Analysis of viscous solution of water soluble polymer AA or AE;F or 1CP;L XRF;-;S 941225 1 9313843 Ti Polypropylene Various (13) Nail-polish film 941572 Various (7) Waxes AE;ICP:L 941698 Various (7) Plastic toys XRF;-;S Various (5) Polyethylenimine AA;F;L 941729 XRF;-;S XRF;-;S 9412325 9412480 Various Paper Various Layered films on polymers SEMICONDUCTORS- A1 Silicon wafer SIMS Measurement of A1 in vapour phase decomposition solutions using microvolume sample preparation with dilute HF; an LOD of 1 x lo8 atoms cm-’ was reported Sample electrode was degreased dried treated with nitric and hydrofluoric acids in a pressure crucible to decompose mixed with boric acid heated and diluted to volume; strontium was used as an internal standard Round robin study for C depth profiling Direct evaporation of sample using laser and resonance ionisation mass spectrometry allowed measurement of contamination present at 10” atoms cm-’; spatial resolution was reported to be better than 200 pm quantification without standards; good agreement obtained with SIMS method temperature LOD reported of 2 x lo9 atoms cm-’ for SIMS but data for TXRF was at least an order of magnitude poorer acetate or 2-methoxyethanol and 20 ul portions of the resulting solution were injected into the furnace; Zeeman-effect background correction was used and the latter preparation was found to produce lower background signals; a detection limit of lppb was recorded for the method using 2-methoxyethanol with an RSD of 5% (n = 3) reported - Non-destructive depth profiling for impurity Study of F distribution as a function of anneal Comparison of techniques for determination of Fe; Samples were diluted to 3% in either 2-ethoxyethyl As for Cu 9412722 9412088 AE;ICP;L Bi Circuit breaker electrodes C Cr Gallium arsenide High purity silicon wafer SIMS MS;laser;S 9313743 9313687 TXRF;-;S 9412508 c u Silicon wafer Silicon Silicon wafer SIMS and TEM SIMS and TXRF 9412785 9313739 F Fe Fe Photoresist AA;ETA;L 9411 192 Silicon wafer TXRF; - ;S 9412508 FeJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 343 R Table 3 (continued) Technique; atomization; analyte form* Element Matrix Sample treatment/comments 1 The surface layer was stripped by application of 4 mol 1-' HBe containing 2.5% Br; the solution was evaporated to dryness and dissolved in HNO for cadmium telluride and in HN0,-HCl for cadmium mercury telluride; in the latter case the solution presented to the atomizer also contained EDTA; an LOD of 2.4 x 10'' atom cm- Ga was reported heterojunction high concentration levels using l60 beam bombardment Quantification of impurity distribution across a Quantitative method for the determination of 0 at Round robin study for 0 depth profiling Quantitative detection of oxygen contamination in sample grown by molecular beam epitaxy Analysis of thin oxide layers on a silicon surface; results were quantified using implanted oxygen standards Variation in sensitivity factor for 0 was studied as a function of alloy composition using ion implanted reference samples Calibration standards made of polyvinyl alcohol and gelatin and filter paper standards were employed; satisfactory correlation with AAS was achieved and film thickness measurements were also made After sample decomposition arsenic was removed by evaporation in the presence of HCl hydroxylammonium chloride and potassium bromide; Si was extracted into IBMK as silicomolybdic acid and injected into the ETA for determination of molybdenum as an indirect measurement Use of platform atomization and a chemical modifier containing orthophosphoric acid and magnesium nitrate for ETA work gave an LOD of 5 pg 8-l for a 250 mg sample; Using ICP-MS with an internal standard improved precision and an LOD of 0.5 pg g- ' for a 20 mg sample was reported Sample was melted under an infra red lamp and a portion of the melt was treated with 3 ml HNO and digested in a Parr bomb; the solution was concentrated to 1 ml diluted to 10 ml and Sn determined at 235.5 nm; 0.01 mol I-' silver nitrate and ammonium molybdate (1 mg ml-' as Mo) were used as matrix modifiers; the calibration graph was linear up to 60 ng ml-1 Sn Study of effect of matrix modifiers including ascorbic acid and palladium nitrate using Zeeman effect background correction; detection limit of 1 x mass% reported The molten sample (0.1g) was digested with 0.5 ml HC1-HNO3 in a Parr bomb for 3 min cooled and diluted; the hydride was produced by treating the sample in a stream of 1.5% NaBH and !% NaOH and trapped in 0.01 mol I-' AgNO,; the determination of Sn was carried out at 235.5 nm; the LOD was 36 pg 8 - I with an RSD of 5.5% (n= 10) reported at the 340 pg 8-l level Detection limits for AA and AE methods reported as 2 x lop6 and 1 x lop6% respectively; a rapid method of detecting thallium in cadmium during purification was also described Rapid method developed for measurement of dopants in single crystals and impurities in polycrystals with detection limits in the range 1014-1016 atoms ern-,; results compared with those obtained by GDMS Removal of tungsten by cation exchange separation on Dowex 50-X4 resin and volatilisation of silicon as the tetrafluoride by treatment with HF-NHO solution; recoveries for Al Ca Cd Co Cr Fe Ga K Mg Mn Na Ni Pb Ti and Zn were 97% Reference 9411146 Ga Cadmium (mercury) telluride AAETA:L Silicon nitrideindium gallium arsenide Silicon SIMS SIMS 94/27 6 5 9313730 0 0 S i 1 icon Gallium arsenide 93/3744 9412704 SIMS SIMS 0 Silicon SIMS 94/2790 0 Aluminium gallium arsenide SIMS 9412797 Pb Electroluminescent calcium sulphide films 94/1562 XRF;-S Si (indirect) Gallium arsenide AA;ETA;L 94/734 Sn Indium phosphide AA or MS;ETA or 1CP;L 941587 Sn High purity gallium AAETA;L 94/644 Sn High purity gallium A A; ETA;L 9412152 High purity gallium AA;ETA;L 9412 5 7 7 Th Various High purity cadmium Indium phosphide AA and AE;-;- 94/934 93 f 3429 AAETA;- Various (15) Tungsten disilicide AA and AE;F or 1CP;L 94/255344 R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 Table 3 (continued) Technique; atomization; analyte form* Sample treatmentlcomments Reference 941334 Matrix separation by distillation with HF and residue dissolved in 0.1 YO HC1 for detection of Al Ca Cd Co Cr Cu Fe K Mg Mn Na Ni Pb Ti and Zn; LODs reported in the range 2.5 x for Cu and Cd to 2.5 x lod4% for Mg and Fe determination of Ba Cd Ga Mg Pb and Si; graphite powder with 5% calcium fluoride added acts as a spectroscopic buffer decomposition with HNO,-HClO,; tetramethylammoniumhydroxide digestion; dilution with acetone; extraction with HC1-IBMK for Fe; and extraction with hot water for K and Na; LODs were 0.1 ppb for Fe and 0.01 ppb for K and Na Samples (100-200 mg) were dissolved in 5 ml of HNO and analysed directly; 10 p1 of a matrix modifier solution containing palladium (3 mg ml-') and magnesium nitrate (2 mg ml-') was injected with 20 pl of sample; RSDs for As Te and T1 were reported in the range 3-11% for contents >0.1 ppm Tellurium powder was mixed 4 1 with graphite powder and 2% gallium oxide; sodium chloride was added into the discharge zone oia a counter electrode method proposed for detection of Mn Pb and Sn ]Extraction chromatography method for (Comparison of several methods including acid Extractionshromatographic matrix separation As for Bi A single crystal was washed with acetone etched with HF-HNO solution dried under an infra red lamp then heated with xenon fluoride in an autoclave at 170 "C; the residue was dissolved in water and analysed; detection limits in the range 0.1-10 pg g-' were reported for Al Cu Fe Ga Li In and Ni Samples were chemically etched with Br and HBr for layer by layer detection of Bi Cu In and Sb Samples were digested an internal standard added and aliquots placed on siliconised quartz glass carriers; LODs were of the order of 0.1 YO m/m for Ce Eu and Tb Study of thin films on substrates produced by plasma vapour deposition and chemical vapour deposition processes; depth profiling of C Cr H N 0 and Ti reported; detection of elements above 10-100 ppm possible Determination of Co Cr Cu and Ni with LODs of 6.6 4.1 3.3 and 3.6 x lo9 atoms cm-2 respectively Determination of trace impurities by tungsten filament electrothermal vaporization into the ICP; the addition of 10 pl of H2S04 to the sample solution was reported to prevent the loss of A1 and Ti Quantitative analysis for impurities using standard samples and relative sensitivity factors Laser ablation followed by resonant-enhanced multi- photon ionisation combined with reflection time of flight MS; LODs in the lppb range were reported for Al B Cr and Fe Element Various (15) Matrix Polycrystalline silicon AA;F;L Various (6) High purity cadmium and tellurium AE;arc:S AA;ETAL 941535 9417 16 Various (3) Photoresist 9411 145 Various (3) High purity cadmium and tellurium AA;ETA;L Various (20) Tellurium AE;arc;S 9411255 Various (3) Cadmium mercury tellurium AE;-;- 9411652 9412089 9412153 Ti Circuit breaker electrodes AE:ICP:L Various (7) High purity silicon AA;ETA;L 9412 156 9412221 Various (4) Various (3) Tellurides Electroluminescent materials 9412264 Various (6) Silicon and tungsten carbide AE;GD;S Various (4) Various Silicon wafers High purity silicon TXRF;-:S AE or MS;ICP:L 941242 1 9412564 Silicon and gallium arsenide Semiconductors SIMS MS;Laser:S 9412740 9412742 Various Various (4) GLASSES- c u Zirconium fluoride Zirconium fluoride AE;ICP;L AE;ICP;L Comparison of extraction and separation of methods for removal of impurities from matrix; removal of Cu at 20.2 pg g- level was achieved in the range 80-96% Comparison of extraction and separation of methods for removal of impurities from matrix; removal of Fe at 4.3 pg g-' level was achieved in the range 8O-96% 941356 941356 FeJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 345 R Table 3 (continued) Element Matrix Hg Soda lime glass Na Radiative glass Pb NIST 610 Glass Se Glass Various (19) Waste vitrification glass Various (1 5 ) Glass Various (4) Zirconium based fluoride glass Various (3) V-As-Ba oxide glass Various (4) Hafnium fluoride Various (10) Glass Various (4) High purity lanthanum fluoride CERAMICS AND REFRACTORIES- A1 REE concentrates c u Superconductors Technique; atomization; analyte form* Sample treatment/comments Reference AA,ETA,L 9411 10 AE;ICP;L 9313793 AE;ICP;L AA;ETA;L 94/29 941277 AA;cold vapour;L Sample (0.5 g <63 pm) was decomposed in a closed vessel using a mixture of HNO,-HClO,-HF and KMnO,; generation of cold vapour was achieved using NaBH Sample was dispersed in 1% ethanol introduced to a graphite cup and the solution evaporated; the glass microsample was introduced in the cup to the ICP for quantitative analysis measurement using double focusing magnetic sector instrument; correction of mercury interference on 204 isotope was corrected by measuring mercury isotopes simultaneously HN03-HC104-HF and Se was selectively extracted with dithizone in CCl,; good agreement was obtain using this method and hydride generation AAS and XRF Fusion of the sample with lithium borate; use of high solids nebulizer to eliminate blockage and optimization of plasma parameters to minimise spectral interference from titanium and uranium; detection of Al B Ca Ce Cr Fe La Li Mg Mn Na Nd Ni S Si Sr Ti U and Zr reported with RSDs in the range 1-5% Sample was fused with lithium borate at 1100 "C for 30 min and the molten material was dissolved in 10% HNO and diluted to 500 ml with water Sample was dissolved in zirconium oxychloride and was analysed directly using 4 mol 1-1 HNO as matrix modifier; results obtained with the method were comparable to those obtained using chelation solvent extraction; detection limits for Co Cu Fe and Ni were reported as 0.05 0.04 0.1 and 0.04 ng g-' respectively Main components were separated from impurities by treatment with carbonate-free sodium hydroxide in a zirconium crucible at 400 "C; determination of As Ba and V carried out with scandium as internal standard; spectral interference on As line at 193.698 nm due to V emission at 193.682 noted The sample (1 g) was heated in 10 ml of HF (48%) the volume was reduced by half cooled and the solution diluted 10 fold with water; LODs for Co Cu Fe and Ni were reported as 1 2 3 and 3 ppb respectively with average precision of better than 10% relative for all elements Laser ablation using a NdYAG laser in Q-switch mode at 15 Hz repetition rate and 80 mJ per shot; the method was applied to the determination of Ba Ce Cu La Mn Pb Sr Ti Y and Zr at levels above 10 pg g- ' Preconcentration of impurities with by leaching with nitric acid which was then analysed directly; LODs for Co Cu Fe and Ni were reported as 1 2 3 and 2 ppb respectively 9411768 AEICP;S 941908 MS;ICP;S Laser ablation of sample and isotope ratio 9313451 Sample was digested in a mixture of 9411271 or 94/25 59 AE;ICP;L 941600 AA;ETA;L 9417 1 3 MS;ICP;S 9411112 AA;ETA;L Use of standard additions method found to eliminate Powdered sample (1 g) was placed in a glass filter need for matrix correction procedure tube and treated six times with 20 ml of 2% acetic acid to dissolve the ceramic matrix and the residue treated twice with 3 ml of HCl (1 1) and the solution placed on a PTFE substrate and evaporated under an IR lamp 9313919 941335346 R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 Table 3 (continued) Technique; atomization; analyte form" AE;ICP;L Sample treatment/comments Reference Element Matrix Hf Scandium oxide Sample (0.1-0.3 g) and concentrated HC1 (1.5 ml) 941706 were gently heated and the dissolution accelerated with 0.2 ml of 5 YO hydrogen peroxide; the solution was evaporated to dryness and redissolved in acid and passed through a bed of Levextral resin with 1-phenyl-3-methyl-4benzoylpyrazol-5- one as stationary phase; the matrix was eluted with 6 mol 1-1 HCl and HF was desorbed quantitatively with 0.5 mol 1-1 oxalic acid; LOD of 0.17 pg 8-l reported mol 1-' HNO,; 100 pl of this slurry was injected in a double channel FI manifold simultaneously with 100 p1 of a 10% lanthanum solution; an LOD of 0.007% for potassium oxide was reported chromatography using a column packed with 2-ethyl hexyl hydrogen 2-ethylhexyl phosphonate- loaded polymer resin by elution with HC1 was reported preconcentration for detection of ng g- quantities of Nd As for A1 The sample (0.1 g) was fused with 10 g sodium 50 mg of sample was dispersed in 25 ml of 0.13 Separation of analyte from matrix by As for K; an LOD of 0.01% for magnesium oxide Use of isotope dilution with chemical carbonate for 30 min at 1100 "C and the melt dissolved in 50 ml water; the solution was filtered and the content of Si in the filtrate was determined at major constituent levels at 251.6 nm Powdered sample (0.5 g) was mixed ultrasonically with 2.5 ml of 0.1% sodium hexametaphosphate and diluted to 50 ml with water; after shaking for 30 min the slurry was analysed in a tantalum carbide coated graphite furnace containing 10 pl of 20% 1-ascorbic acid as matrix modifier; LOD of 0.15 ng Sn reported Sample (0.1 g) was decomposed by heating with mixture of water (20 ml) H,SO (10 ml) and HNO (5 ml); the solution was filtered and diluted to 100 ml with water prior to determination of V at major levels at 318 nm As for Hf; LOD of 0.14 pg 8-l reported Samples were decomposed using 50% nitric acid and the solution diluted with water and 20% sodium chloride added for determination of K and Rb or 20% potassium chloride added for the determination of Li and Na Addition of 70% alcohol reported to improve sensitivity for the determination of 14 REEs Method for the determination of Ce Dy Er Eu Gd Ho Nd Pr Sm and Y in high purity sample yielded lowest concentrations detected in the range 0.1-4.0 pg ml-l with recoveries from 89-107% reported Samples were dissolved in HNO and analysed using a 56 MHz ICP with a high resolution spectrometer; interference free spectral lines were found for the determination of Dy Er Eu Gd Ho Lu Tb Tm and Yb; recoveries were reported in the range 84-106% for the method Use of a high resolution magnetic sector instrument to overcome interferences on Lu Tb Tm and Yb from gadolinium matrix; Doubly charged ions were used to enhance analyte selectivity to achieve solution detection limits for these elements in the range 0.05 to 3 ng 1-1 Study of the use of ETV to improve sensitivity and remove solvent effects via a reduction in oxide levels; it was reported that Lu and Tb were determined at a level of 0.01 pg g-' in high purity samples IS Cement AE;FS 9313380 La Terbium 9313932 AE;ICP;L AA;F;S MS;ICP;L 9313380 9412808 Mg Cement Nd Lanthanum compounds XRF;-;S AA;F;L 9313919 941952 Si REE concentrates Si Superconductor AA;ETA;S 9412565 Sn Titanium dioxide Superconductor AA;F;L 941952 v Zr Scandium oxide Alkali Superconductors metals (4) AE;ICP:L AE;F;L 94/706 94/ 1 0 1 7 REEs Cerium oxide REEs Terbium oxide AE;ICPL AE;ICP;L 9313529 9313556 REEs (9) High purity yttrium oxide AE;ICP;L 941497 REEs Gadolinium oxide MS;ICP;L 941576 Gadolinium oxide MS;ICP;L 941632 REE'sJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 347 R Table 3 (continued) Element Matrix REEs (10) Terbium oxide REEs Thulium oxide REEs Oxide concentrates REEs Holmium oxide Various Silicon carbide and nitride ceramics Various Tantalum and Niobium oxides Various (10) Superconductors Various ( 1 1) Lead zirconate titanate Various Zirconium oxide Various (4) REE oxides Various ( 11) Silicon carbide ceramics Technique; atomization; analyte form* AE;ICP;L AE;ICP;L AE;ICP;L AE;ICP;L MS;ICP;S AA and AE;F and DCP;L AE;ICP;L MS;ICP;L AA;-;L AE;ICP;S Various (4) Superconductors and quartz AE;MIP;S Various (8) Lanthanum oxide AE;ICP;L Various ( 5 ) Superconductors AA;F;L Sample treatmentJcomments Reference 9411057 Study of effect of ICP operating parameters on the determination of Cr Dy Er Eu Gd Ho Nd Pr Sm and Y; LODs were reported in the range 0.1-4 pg ml - and recoveries were between 89 and 0.1 g sample was dissolved in 1 1 HC1 heated gently to near dryness and diluted to 10ml with 2% acid; detection limits were reported in the range 0.01-0.6 pgml-' for Ce Dy Er Eu Gd Ho Lu Nd Pr Sm Tb Y and Yb Samples were decomposed in dilute HNO and the insoluble residue fused with sodium carbonate sodium borate or lithium borate; LODs for 15 elements were reported in the range 0.01-0.3 mg 1-l Sample (0.05 g) was ignited at 850°C for 2 h dissolved in 1 1 HC1 mixed with 7 ml of anhydrous ethanol and diluted to 10 ml with 5% acid; detection limits were reported for oxides of Dy Er Tb and Tm at 0.002% and for Y at 0.0003%; RSDs were reported in the range 0.15 g of silicon carbide was decomposed with a 107% 2.8-7.4% mixture of 5 ml H,SO 2.5 ml HNO and 2.5 ml of HF in a PTFE pressure vessel at 230°C; 0.3g of sintered silicon nitride sample was decomposed with a mixture of 6 ml HNO and 4 ml HF heated at 170 "C Direct analysis of samples pelleted with polyvinyl alcohol for trace impurities using laser ablation; detection limits were reported to be less than 1 pg g-' for Al Ag Fe Mg Mn Nb Sn Ta Ti and W; problems experienced with memory effects and poor reproducibility were discussed Methods were developed for the determination of major components (Ba Cu Y) dopant elements (Al As Ba) and background impurities (Cr Co Mn Ni Description of a sample decomposition procedure for the determination of major components (Pb Ti and Zr) and additives (Cd Co Mg Mn Nb Ni Sb and Sr) H,S04 solution using ion exchange separation; matrix effects in ICP-MS were corrected using In as an internal standard; ultra trace REEs and Co Cu and Ni were determined Sample (0.3-0.5 g) was moistened with water dissolved by heating with 3 ml HC1 and evaporated to near dryness; the residue was dissolved in 20 ml of water and the pH adjusted to 3-4 with dilute HCl or NaOH; the resulting solution was treated with APDC and extracted with IBMK; Fe Ni PB and Zn were determined in the organic phase and recoveries for the method were in the range 86-103% of 3 pm and de-ionised water was added to form a slurry which was introduced to the ICP; Al B Ca Co Cr Cu Fe Na Ni Ti and V were determined by reference to pre-analysed samples using internal standards for calibration; LODs were better than 1 ppm for all analytes Laser ablation of sample into MIP and measurement of emission spectra for Al Fe Mg and Si by time gated detection A column chromatography method with D-238 reins was used to separate analytes (Co Cr Cu Fe Mn Ni Pb and V) from the matrix; detection limits in the range 0.2-2.8 pg g-' were reported Sr Pb Pt and Run in Ti-Ba-Ca-Cu oxide materials Matrix removal of 97% of zirconium in a dilute Sample (4 g) was ground to an average particle size Study of interelement effects in the detection of Bi 9411230 9411731 9412570 9313382 9313388 9313418 9313646 9313769 941123 941195 941289 941389 941520348 R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 Table 3 (continued) Element Matrix Various (5) Ceramics Various (4) High purity alumina Various (3) Superconductors Various (1 1) Niobium oxide Various (4) Silicon carbide ceramics Various ( 14) Lead-zirconate ceramics Various ( 5 ) REE oxides Various ( 15) Graphite Various (18) Scandium oxide Various (12) Graphite powder Various (8) Portland cement Various (4) Zirconia based ceramics AA;ETA;L 941989 AF;ICP;L 9411 0 16 AEarc; S AA;F;L 94 f 1034 9411037 XRF;-;S 94/1166 AA;F;L AE;ICP;L AE;ICP:L AE;ICP;L 9411221 9411300 9411 6 1 3 9411 6 19 9412293 9412397 Technique; atomization; analyte form* Sample treatment/comments Reference AA and AE;F;L Sample (0.1 g) was digested with lithium borate (1 g) 94J735 in a muffle furnace at 1000 "C before dissolution in HNO and dilution with water; the LODs for Ca Fe K Mg and Na were reported as 70 50 50 8 and 100 pg 1-1 respectively; RSDs were in the range 0.5-2% Sample (250-350 mg) was heated at 220 "C for 18 h with 10 ml of 4 moll-' H2S04 under pressure; after cooling an aliquot of the digest was adjusted to pH 3 using 4.5 mol 1-' NH,OH and extracted with DDC into chloroform; the method was applied to the determination of Cd Cu Fe and Pb as impurities in commercial samples of alumina powder HNO and the solution was diluted to 100 ml with water; 2 ml of a surfactant solution was added and analysis was carried out by AF using HCL excitation; LODs for Ba Cu and Y were reported as 500 50 and 1500 pg I-' respectively Sample was ignited in a platinum dish at 800 "C for 2 h and the residue blended 2 1 with graphite powder and 5% sodium chloride-fluoride carried which was packed into the cavity of a graphite rod electrode Samples were decomposed by heating at 650 "C with a 2 1 mixture of sodium carbonate and sodium nitrate and water added; the insoluble residue containing alumina was fused with a 3 2 mixture of sodium carbonate and sodium borate at lo00 "C and dissolved in HCl; LODs for Al Cr Fe and Mn were given as 1.0 0.5 0.45 and 0.35 pg 1-' respectively Powdered sample was mixed with silica and lithium borate in the ratio 3 3 22 and the mixture was heated for 15 min in a muffle furnace at 950 "C; the melt was poured into a vitreous carbon crucible and cast into a mould which was annealed at 550°C to form a disk for the determination of Ba Bi Cd Cr La Mn Nb Ni Pb Sr Ti W Zn and Zr 1 g of lanthanum or yttrium oxide was wetted with water and evaporated to dryness and redissolved in water and dilute HC1 and trace elements were coprecipitated with APDC and extracted into IBMK Cd Co Cu Fe and Ni were determined in the organic phase directly; sensitivities for these elements were reported to be improved by 10-30 fold and recoveries were reported in the range Sample was decomposed with 5 ml concentrated 98-11OYo MS and AA; ICP Oxygen plasma ashing at 400°C was employed prior to the detection of Cr Cu K Na Ti and Zn; Ashing at 880°C in an electrical furnace with a quartz tube was employed for the preparation of Al B Ca Co Fe Mg Mn Ni and V Extraction chromatography based on a trioctylphosphine oxide-Levextrel resin column was used to separate trace impurities in high purity sample; improved sensitivity was achieved using end on viewing of the plasma; LODs were reported in the range 0.8-4 pg 8-l for 0.1 g of sample 0.5 g of sample was decomposed with 20 ml of HNO H2S04 and 4 ml of under pressure at 250 "C for 72 h; excess HNO was removed by heating on a hot plate and the solution diluted to 50ml with water and Al Ca Cr Fe K Li Mg Na Ni Sr Ti and V determined by ICP-AES; RSDs were reported to be < 10% for these elements at the 1 pg g-' level (n = 5 ) Decomposition of sample with 10% HC1 followed by detection of Co Cr Cu Fe Mn Ni Ti and V A study of spectral interferences in the determination of Ce Th Ti and Zr at major and trace levels; LODs for Th were 15ppb at 283.231 nm and 30 ppb at 326.267 nm and 2ppb for Ti at 334.941 nm and 336.121 nm and ETA AE;ICP;LJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 349 R concentrations of elements in the soluble state for plastics which constitute the whole or part of the toy. The limits for some of the elements are as follows As Cd Cr and Hg 100 mg kg-' Pb and Sb 250 mg kg-' and Ba 500 mg kg-l.An X-ray Juorescence method has been proposed for the determination of these elements in plastic components for toys (94/698). Mineralization of the sample was achieved by decomposition of the organic matrix with molten sodium hydroxide using sodium nitrate as an auxillary oxidant. The species of interest were separated from solution using an ammonia buffer (pH 8.5) with sodium DDC and sodium rhodizonate and iron(II1) which acts as a carrier. The precipi- tates thus formed were collected on filter paper and examined by XRF. Results were obtained which were comparable with an AAS method. The plastics industry has had to rely on in-house materials for standardization in the absence of suitable reference mate- rials. Owing to the toxicity of Cd many countries are now restricting the levels of the element which may be used in plastics. In Europe an international measurement evaluation programme (IMEP-2) has been carried out for the certification of Cd in polyethylene.Results from laboratories participating in the study have now been published (93/3583 94/1631). The levels of Cd as determined by ID-MS were found to be 40.9 75.9 198 and 407 mg kg-l respectively (93/3583). Homogeneity testing of the material was carried out using solid sampling AAS (94/1631). A microsample (60-250 mg depending on Cd content) was placed in the graphite furnace and analysed directly using Zeeman-effect background correc- tion. Approximately 60 analyses were carried out on the material and the homogeneity assessments and detection of minimum sample mass were discussed.An interlaboratory collaborative study (13 participants) of the determination of Cd in wrapping paper using ETAAS may also be of interest (94/37). The mean concentration reported was 59 ppb Cd. A simple and rapid technique has been described for the determination of low concentrations of Ge which is a catalyst used in the production of polyethylene terephthalate (94/1718). The two major Ge I ICP-AES lines at 265.1 18 and 303.906 nm were compared in terms of SBR LOD background equivalent concentration and inter-element interference. Under optimized conditions the detection limits reported for the two lines were 13.4 and 30.1 ngml-' for Ge at 265.118 and 303.906nm respectively. It was recommended that closely matrix matched standards should be used for Ge determinations.Aluminium and titanium are used in catalyst formulations for the manufac- ture of polypropylene (94/2251). A method has been described in which lg of the sample was melted in a platinum crucible and A1 and Ti standards added. The solution was evaporated on a sandbath at 250-300°C. The carbon residue was mixed with 0.5 ml nitric acid and heated gently. This procedure was repeated three times. After the addition of 0.5 ml sulfuric acid (1 3 v/v) the acid was evaporated and the residue containing A1 and Ti compounds was fused with potassium bisulfate initially at 380-420°C to avoid losses during the evaporation of water. The mixture was then melted at 800°C for 2mins and dissolved in water acidified with dilute sulfuric acid.Aluminium and titanium were determined by ICP-AES at 308.315 and 336.121 nm respectively. Detection limits for A1 and Ti were reported as 0.16 and 0.04 pg ml-l. There is growing interest in the use of lasers for direct sampling of polymeric materials. For quantitative elemental analysis LA-ICP-MS is most likely to provide advantages in terms of sensitivity over existing solid sampling techniques (94/C1882). However a variety of instruments systems have been applied to the examination of polymers including LA-ion trap-MS (94/288) laser desorption-ion mobility spectrometry for polymer characterization (94/709) laser induced plasma AES for rapid survey analysis (94/2392) and laser mass spec- trometry for elemental analysis (94/2802). A common feature of most of these approaches is the use of the Nd YAG laser with an output wavelength of 1024nm which allows good coupling to the sample.The characterization of carbon fibre composite materials has been the subject of interest in the last year. Two SIMS studies of the fibre matrix interfaces have been published (93/3512 94/2777). Carbon isotope ratio mass spectrometry has been used to study the oxidative gasification of fibre reinforced composites (94/1360). Other abstracts which may be of interest include the determination of oxygen containing co-monomer content by XRF (94/2351) and the detection of polyacrylates in air by ICP-AES using an indirect method for Cu following co-precipitation (94/779). 3.2. Semiconductors 3.2.1. Silicon based materials The literature concerning the characterization of silicon-based semiconductors continues to be dominated by reports of the application of SIMS and related techniques.From an analytical point of view the calibration of instrument response is critical to achieving accurate elemental analysis. Consequently there have been a number of studies concerned with understanding and improving the quantitative performance of SIMS. Ion implanted standards are widely used in SIMS for depth profile quantification (93/3696). However the standard will be dam- aged or amorphized to an extent dependent on the mass and dose of the implant and the SIMS response may be different for analyte existing in a crystalline state. A method was proposed for detecting changes in erosion rate due to the material state.The main sources of error in the SIMS measure- ment were attributed to inaccuracies in crater depth measure- ment and the inability to accurately detect the primary beam current. The limiting parameters for quantification of As B and P using implants were determined. The effect of localized reactive species on quantitative SIMS analysis in silicon has been investigated (93/3697). Ion yields for uniformly implanted B and Si were found to be enhanced by fluorine and oxygen. The effect was found to be different for B and Si and linear except in the case of fluorine levels of 1 x 1OI6 atoms cm-2 implanted in the sample where a quadratic relationship was evident. It was concluded that a ratio of dopant-to-matrix element signals must be applied to achieve accurate quantifi- cation.A study has been made of the potential of nitrogen molecular beam ion bombardment of silicon for the determi- nation of elemental implants (93/3589). It was reported that a high efficiency was achieved for layer by layer SIMS detection of As B Cl F K Na P and S with a significant intensity noted for secondary ions of BN-. It was concluded from the LODs obtained for the detection of C1 F Na S and Zn that molecular nitrogen beams yield equivalent or better perform- ance than caesium or oxygen ion beams. Improvements in the determination of P in silicon by SIMS has been reported (93/3747). A new background subtraction procedure has been developed which utilizes the ability to detect the position of p n-junctions in silicon from the intensity variation of a matrix ion species.Using this procedure it was possible to improve the detection limit for P in n-well structures by more than one decade of concentration to 1015 atomscm-' using an ion probe with low mass resolution. The results of a round robin study of the German SIMS forum for the determination of 0 in silicon has now been published (93/3744). As a result of the information from depth profiles of 0 gathered in this exercise a procedure was recommended to allow rapid analysis. In another study the determination of 0 in silicon and gallium arsenide using SIMS was described (93/3678). Implanted 0 in the sample was used as an internal standard. It was found possible to distinguish between signals from bulk and surface 0. A straightforward method for the quantification of 0 in silicon at high con- centrations has been published (93/3730).The sample was bombarded with an l60 molecular oxygen ion beam and350R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 quantification was found to be possible using the l80 isotope. The method was found to work for both positive and negative ion modes and gave linear calibrations. The characterization of oxygen precipitates by imaging SIMS (93/3751) and the SIMS quantification of thin oxide layers on silicon surfaces (94/2790) may also be of interest in this context. The total-reflection XRF technique is now firmly established as a sensitive and selective means of achieving quantitative analysis in a silicon wafers. The basic principles of the technique in this field of application have been the subject of recent reviews (94/2222 94/2421).Comparisons of TXRF with com- petitive techniques such as SIMS or vapour phase dissolution AAS may be of some value (93/3739,93/3755). The deposition characteristics of metals contaminants from hydrofluoric acid- based process solutions onto silicon wafer surfaces have been investigated using TXRF (93/3870). A range of elements includ- ing Ag Au Cr Cu Mn Mo Pb Sn Ti and W were added to buffered oxide etchant and hydrofluoric acid solutions used in wafer cleaning. It was found that while most contaminant deposition characteristics were simple in some cases there was a complex interdependency on other factors including bath type contaminant level and the presence of other species. Total reflection XRF has also been used for non-destructive depth profiling of impurities in silicon wafers (94/2508).Quantification for Cu and Fe was obtained without using standards and the LODs were reported to be of the order of 10" atoms cmP2. Satisfactory agreement was achieved with data produced by a SIMS method. Examples of the use of TXRF for near surface layer analysis have also been published (94/2429 94/2476). Trace metal contaminants on silicon wafers have been determined by flow injection ICP-MS (94/1408). One or more Si wafers were loaded onto a specially constructed vapour phase decomposition box containing a reservoir of hydrofluoric acid. The exposure time was dependant on the thickness of the surface oxide layer. After the exposure period a single drop of acid was placed on the surface of the wafer and carefully rolled across the surface to extract the trace metals.The drop was then transferred to a small sample tube and injected into the nebulizer assembly. Calibration was achieved using multi-element standards. Recovery of trace metals spiked onto untreated wafers was in the range 90-110%. Limits of detection for a number of common contaminants were of the order of lo8 atomscm-2. In a similar study the analysis of condensed acid vapour from the surface of a silicon wafer has been reported (94/C1920). In order to achieve low detection limit on a microsample (50-200 pl) .a direct injection nebulizer was used to introduce sample to the ICP-MS. The nebulizer was able to operate at sample rates as low as 50 pl min-' and consumed 100% of the sample which was necessary for the analysis of such small samples.The detection of trace levels of impurities in high purity silicon has been investigated using ETV sample introduction for ICP-MS and ICP-AES (94/2564). Samples were prepared using vapour-phase pressurized decomposition. The addition of 10 pl of sulfuric acid prevented the loss of A1 and Ti during the sample preparation stage. A tungsten filament atomizer was used to introduce the sample to the ICY. However since the sulfuric acid present in the sample was found to erode the tungsten filament the acid was removed prior to analysis by cation exchange chromatography. Detection limits for the ICP-AES system were achieved in the low ppb range. Further improvements in sensitivity (except for Ca and Fe) were not surprisingly obtained by utilising ICP-MS for detection. The determination of tetraethoxysilane (TEOS) vapour by high resolution ICP-MS has also been reported (94/C1989).The conventional nebulizer spray chamber system were removed and a gas sampling system was installed compris- ing a manifold with mass flow controllers designed to allow mixing and dilution of the sample with argon or an argon oxygen mixture. It was reported that the high resolution ICP-MS system provided an advantage in the ability to separate analyte and polyatomic species at the same nominal mass although no examples were given in the abstract. Quantification of impurities in TEOS vapour were achieved using this approach. 3.2.2. Gallium based materials The majority of abstracts received in the year under review relating to gallium based semiconductor materials concerned the application of SIMS for quantitative depth profiling studies.One reference which will be of general interest in this area is a report of the round robin study by German SIMS users of the depth profile of C in Ga As (93/3743). Relative sensitivity factors (RSFs) are used in SIMS to provide what is effectively semi-quantitative analysis of materials. A study has been made of the long term stability of relative sensitivity factors for SIMS in the analysis of semiconductors such. as gallium arsenide (93/3704). Two identical magnetic sector instruments with identical mass spectrometers were used to assess changes in RSFs over a period of five years.It was concluded that the variation was of the order of 50% for a range of ions and that the results supported the idea that RSFs could be reliably transferred between SIMS instruments of the same type. It has been reported that the reproducibility of quantitative measure- ment using SIMS is influenced by the energy distribution of sputtered elements (94/1521). The energy distribution of As ions produced by the bombardment of gallium arsenide by caesium were compared as measured in the middle of the sample holder and at a distance 0.7mm from the edge. The possible use of the pre-peak for singly ionized elements was studied using argon and oxygen positive ion bombardment as a function of operating conditions. It was found that quantitat- ive analysis could best be performed when elements with a low positive ion yield were detected.Newer materials such as gallium antimonide have been found to suffer significantly from swelling as a result of high energy ion implantation or low energy caesium bombardment used for SIMS investi- gations (94/1452). A study was made of this phenomenon using oxygen and caesium ion bombardment in the energy range 1.25-14.5 keV with doses from to >lo" atomscmA2. It was reported that the swelling was due to damage caused by primary ion bombardment. This had the result of reducing depth resolution and modifying ion yields and will hence influence the accuracy of quantification. Aluminium gallium arsenide structures are usually multi- layered and there has been a significant interest in the depth profiling of such materials.Two separate studies have con- firmed that oxygen bombardment causes surface roughening of aluminium gallium arsenide resulting in degraded depth resolution (93/3718 94/1342). In the former it was noted that 110 similar effect was found for caesium argon xenon or nitrogen ion bombardment. A quantitative SIMS study of this sample matrix indicated that the use of caesium ion bombard- ment is preferable to oxygen ion bombardment for minimiz- ation of background signals (94/1493). Alternative methods for quantitative depth profiling of multi-layer systems of this type have been described including laser-induced sputtered neutral mass spectrometry (93/3623) and sputter initiated resonance ionization spectroscopy (94/1418).In the latter paper a depth resolution of 2nm was demonstrated using a 0.5 keV argon primary ion beam. The determination of individ- ual layer thicknesses in multi-layer aluminium gallium arsenide structures has also been investigated using SIMS and TEM (94/1405) SEM and SIMS by conversion of time of sputtering to a depth axis (94/1531) and energy dispersive XRF employing selective excitation and variable X-ray geometry (94/1582). Only a few abstracts were received concerning the appli- cation of ETAAS to the characterization of gallium based- semiconductors. Three of these publications concerned the determination of Sn in high purity gallium. An ETAAS system incorporating Zeeman-effect background correction was usedJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 351 R in conjunction with matrix modification to detect impurity Sn levels (94/2152). The effect of ascorbic acid and palladium nitrate on the Sn signal was evaluated in the presence and in the absence of the Ga matrix. A lower limit of determinable content for Sn in gallium using the method was given as 1 x mass%. In a different approach a sample was melted under an infra red lamp and a portion cooled treated with nitric acid and digested in a Parr pressure bomb (94/644). The solution was concentrated by heating diluted and analysed using ETAAS at 235.5 nm. Silver nitrate and ammonium molybdate were employed as matrix modifiers. The calibration range was reported to be linear up to 60 ng ml-' of Sn and recoveries of analyte of >80% were achieved.The same authors have also published an alternative method based on a similar dissolution procedure involving the separation of Sn as the hydride (94/2577). In this case the diluted sample was merged with a stream of 1.5% sodium tetrahydraborate in 1% sodium hydroxide and the resulting hydride was trapped in 0.01 moll-' silver nitrate. Tin was determined in the resulting solution by ETAAS. A detection limit of 36 pg kg-' was reported for the method with recoveries in the range 90-100%. At 340 pg kg-' Sn the RSD was found to be 5.5% (n= 10). An indirect method has been proposed for the determination of Si in gallium arsenide by ETAAS (94/734). After sample decomposition arsenic was removed by evaporation in the presence of hydrochloric acid potassium bromide and hydroxylammonium chloride and Si was extracted into IBMK as silicomolybdic acid.Silicon was detected indirectly as Mo in the organic phase by direct injection into the ETA. A detection limit of 0.7 pg g-' Si in gallium arsenide was reported. The precision of the overall procedure was in the range 5.9-14.8% relative for Si contents of 1.4-2.7 pg g-'. 3.2.3. Cadmium mercury telluride- and indium phosphide-based materials Atomic spectrometric methods remain popular for the determi- nation of major constituents and trace impurities in cadmium mercury telluride and associated materials and precursors (93/4080). There would seem to be few applications of ICP-AES in this area although arc emission spectrometry papers continue to appear (94/535 94/1255 94/1652).A number of AAS procedures which may be of practical interest have been reported. These include the determination of Th in high purity cadmium (94/934) and the measurement of As Te and Th in high purity cadmium and tellurium (94/1115). The physical structure of these materials is important and AAS has been used in the layer-by-layer determination of Ga as impurity in cadmium telluride and cadmium mercury telluride (94/1146). Surface layers were removed from the material by chemical etching with 4 mol 1-l hydrobromic acid containing 2.5% bromine. The solution was evaporated to dryness and the residue dissolved in nitric acid. Gallium was determined in the 2-30 ng ml-' range by ETAAS. The same authors have also described the application of this sampling approach to the determination of major and impurity levels in cadmium telluride cadmium mercury telluride and lead tin telluride (94/2156).Impurity elements including Bi Cu In and Sb were detected by AAS. As with other materials there have been investigations reported of the use of SIMS for quantitative analysis of cadmium mercury telluride. These include the detection of compositional changes using negative ion SIMS (94/1530) and the determination of Na contamination introduced by cleaning reagents (93/3701). A review of the RSFs for positive ion SIMS applied to cadmium mercury telluride matrices may be of some interest (93/3554). Laser scan mass Spectrometry has been applied to impurity survey analysis of cadmium mercury telluride (94/1461). A focused Q-switched Nd YAG laser was raster scanned across the sample which was placed in the source chamber of a high resolution mass spectrometer.It was observed that surface impurities were effectively removed in the first scan and that true levels of impurities could be measured in subsequent scans. The technique was applied to the quantitative determination of P and I. In a similar approach LMMS was applied to the elemental analysis of polished cadmium telluride crystal (94/1426). The accuracy and reproducibility of the technique was assessed by statistical treatment of data obtained from the analysis of numerous sample specimens. In contrast to previous years there have been very few abstracts received concerning the analysis of indium phosphide. A method for the determination of trace element impurities in indium phosphide by AAS has been published (93/3429).Detection limits in the range 1014-1016 were obtained without using preconcentration. The method was also applied to the measurement of dopants in indium phosphide single crystals. Results were compared with those obtained by GDMS. Two independent methods have been proposed for the determi- nation of Sn in doped indium phosphide (94/587). An electro- thermal AAS method was described which utilized platform atomization and orthophosphoric acid and magnesium nitrate as matrix modifiers. A detection limit of 5 pg 8-l was obtained for a 250mg sample using this approach. The determination was also carried out using an ICP-MS procedure and a detection limit of 0.5 ng 8-l was reported for a 20 mg sample.Interference effects were studied for both methods and it was recommended that matrix matched calibration standards should be employed. The developed methods were applied to samples containing 35-149 pg g-' Sn and the RSDs were found to be in the range 4.3-12.9% for ICP-MS and 2.0-3.4% for ETAAS. Secondary ion mass spectrometry was used to investigate ion implantation damage in indium phosphide after high tem- perature annealing (94/2681). Dopant ions (Be Si) and non- dopant ions (B H N 0 P) were studied. The application of encapsulation to the SIMS study of indium phosphide wafers has been reported (93/3746). The method was used to quanti- tatively detect C and Si contamination on wafer surfaces. 3.3. Glasses Ceramics and Refractories 3.3.1.Glasses The demand for higher purity glass and optical jibre materials and precursors has led in turn to a requirement for suitable methods for trace element analysis in these matrices. Atomic absorption spectrometry undoubtedly has the sensitivity required for many applications and a significant proportion of the literature published in the year under review is devoted to developments in this field. The determination of Hg in glasses is problematic primarily because of the possibility of analyte losses during sample preparation (94/1768). A method has been described in which a soda-lime glass sample was decomposed under pressure in a nitric-perchloric-hydrofluoric acid mixture containing potassium permanganate. Mercury was detected by cold vapour AAS using sodium tetrahydrabo- rate as the reducing agent.Good recoveries of Hg were claimed for the procedure. A similar acid digestion procedure was recommended for the determination of Se in glass using hydride generation AAS (94/110). However it was noted that inter- ferences gave rise to a suppression of the Se response and in such cases Se was extracted into carbon tetrachloride using dithizone and determined by ETAAS. A series of papers have described the application of ETAAS to the determination of trace elements in high purity hafnium and lanthanum fluorides and zirconium-based glass (93/4029 94/71 3 94/277 94/127 1 94/2259). For each method Co Cu Fe and Ni were determined at low ppb levels following dissolution and/or extraction procedures (see Table 3). The application of laser and GD techniques for direct solid sampling of glass continues following on from a significant increase in research activity in this area as identified in last352R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL.9 year's review (see J Anal. At. Spectrom. 1993 8 337R). A Nd YAG laser was coupled to an ICP-MS system and applied to the determination of trace elements in 10 glasses (94/1112). The laser was operated in Q-switched mode at a pulse rep- etition rate of 15Hz and an energy of 80 mJ per shot. An NIST Glass standard (SRM 612) was used to calibrate the instrument at half-daily intervals. The system was used to determine Ba Ce Cu La Mn Pb Sr Ti Y and Zn at levels below 10 ng g-' for the REEs and up to 2000 pg 8-l for Mn. Agreement with certified values for the SRM was obtained to better than 20% relative.Laser ablation ICP-MS has also been applied to the measurement of lead isotope ratios (93/3451). The isotopic composition of NIST SRM 610 glass was estimated using an ICP source interfaced to a double focusing magnetic sector mass spectrometer equipped with 7 Faraday detectors for simultaneous measurement of Pb 204 206 207 and 208 isotopes. The instrument was also used to measure mercury 202 and 204 isotopes and thallium 203 and 205 isotopes in order to make corrections for mass bias effects and interference on the Pb 204 isotope. The Nd YAG laser was operated in Q-switched mode with an energy output of approximately 2 mJ per shot and generated craters of less than 40 pm in diameter and between 60 and 80 pm deep.Each analysis comprised the measurement of approximately 12 craters in the SRM Glass repeated 5 times. Isotope ratios found using this approach agreed well with those determined by TIMS. Marcus (94/1501) has reviewed developments in GDMS for non-conductive materials including glasses. The use of a tantalum secondary cathode to overcome difficulties in the sputtering of oxide glass materials provides an alternative method for the analysis of non-conducting samples by GDMS and details of the analytical performance of this approach referred to in last year's ASU have now been published (93/3368 see also J. Anal. At. Spectrom. 1993 8 337R). 3.3.2. Ceramics and refractories A range of techniques have been applied to the analysis of non-oxide ceramics in recent years and it is evident from the literature that advances being made at present are in an incremental phase.A range of options exist for the analysis of silicon carbide and papers have been published on mixed acid pressurized sample decomposition for ICP-AES (93/3382) slurry atomization in ICP-AES (94/195) borate carbonate fusion for FAAS (94/1037) and the application of ICP-MS for the determination of impurities in single crystals (94/2550). Perhaps the most interesting development reported involved the use of ETV-ICP-AES for the direct analysis of ceramic powders (94/1079). An interface was devised which was designed to ensure effective transport of analyte vapour from the graphite crucible ETV into the plasma. The interface device made of boron nitride provided a gas tight enclosure resulting in a 12mm transport distance between the base of the crucible and the ICP torch.A region of low pressure was created at the front of the ring jet orifice of the device which caused the analyte vapour to be sucked out of the crucible and into the injector tube of the torch. This vapour was surrounded by carrier gas flowing parallel to the injector tube walls. It was reported that analyte losses were minimized using the device for the analysis of ceramic powders. The same authors have also published work on the optimization of ETV-ICP-AES for the detection of impurity elements in silicon carbide (93/3367). A range of matrix modifiers were evaluated on the basis of qualitative and quantitative assessment of reaction products using SEM EDXRF and ICP-AES.It was concluded that the complex modifier barium oxide-cobalt fluoride (1 1) decomposed almost totally allowing the total evaporation of impurities into the ICP. A few reports were received concerning the use of surface analysis techniques in the examination of ceramics and refrac- tory materials. A comparison has been made of secondary neutral MS and Auger spectrometry for the analysis of silicon carbide silicon nitride and boron nitride materials (94/1430) Depth profile information was obtained and studies were also made of surface functionality. The determination of oxygen in aluminium nitride has been investigated in two SIMS studies (93/3592 94/1539). The quantification of trace impurities in materials such as titanium nitride by SIMS is hindered by the lack of information about relative secondary ion yields for the elements of interest (94/1419).Consequently RSFs for a range of ions implanted into the nitride matrix were collated. It was noted that the use of molecular ions could be used to improve detection limits for some elements with mass interferences beyond the resolving capabilities of SIMS instruments. Application of SIMS to the study of isotopic labelling in the hydroxylation of titania surfaces (93/3719) coated titania pigments (94/1494) and sol-gel prepared barium titanate thin films (94/2773) may also be of interest. Zirconia is finding increasing use as a refractory material in ceramic applications and there is a need to analyse these materials for major components dopants and impurities. Thus the determination of Ce and Zr as major constituents and Th and Ti as minor components by ICP-AES has been described (94/2397).A method was developed based on mixed acid dissolution which allowed the detection of all these elements in the same solution. Limits of detection were reported for Th and Ti of 15 ppb and 2 ppb respectively using the proposed method. An anion exchange matrix removal method was employed in order to determine ultra trace impurities in zirconium oxide by ICP-MS (93/3769). It was found that providing that the zirconium concentration in the sample solution was <400 ppm matrix effects in ICP-MS could be corrected by use of indium as an internal standard. The anion- exchange method carried out in dilute sulfuric acid solution was found to be effective in removing 97% of the zirconium matrix.The method allowed the determination of REEs and Co Cu and Ni at ultra-trace levels. The determination of major and minor elements in zirconia and lanthanum-doped lead zirconate titanate piezo-ceramics by ICP-AES has been described (94/700). Samples of these materials were prepared as targets and were converted to thin films on quartz plates by r.f. sputtering. The films were dissolved in hydrochloric or sulfuric acid and analysed by ICP-AES. The RSDs were reported to be in the range 1-3% for major and minor components and 3-8% for trace components. Methods for the determination of Cd Co Mg Mn Nb Ni Pb Sb Sr Ti and Zr by ICP-AES (93/3646) and Ba Bi Cd Cr La Mn Nb Ni Pb Sr Ti W Zr and Zn by WDXRF may also be of some interest.A few papers have been received concerning the characteriz- ation of aluminium oxide materials. The distribution of elements in an alumina-zirconia ceramic fibre-glass composite has been studied by SIMS (94/2717). The materials were fabricated with and without a tin dioxide interphase and a qualitative comparison of the elemental distribution in the composite was made. It was found that tin dioxide served as an effective barrier between the alumina-zirconia and silica- based glass. The distribution of calcium and magnesium oxides in sintered aluminium oxide ceramics has been investigated by SIMS (94/1508). Compositional images of the phase constitu- ents were obtained. A laboratory-developed GDMS system with low mass resolution has been applied to the analysis of aluminium oxide (94/607).The sample was mixed and com- pacted with copper to prepare a conducting sample in the ratio 1 5. Detection limits were obtained for interference free elements such as Fe Ga Mg and Na which were of the order of a few pg g-'. The advantages of r.f. GD sources for the analysis of non-conducting ceramics may soon become appar- ent (94/C1878,94/C1879,94/C2013). The majority of abstracts received concerning the analysis of superconducting ceramics reflected the prevailing interest in the yttrium-barium-copper oxide (Y-Ba-Cu-0) system. AsJOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 353R with most materials with a functional structure the fabrica- tion and characterization processes can be interlinked.Consequently the plasma sources used to deposit thin films of superconductive material may have more general analytical application. A d.c. 94.92 MHz hybrid plasma magnetron sputter- ing system was used for fabricating thin films of Y-Ba-Cu-0 (94/357). The cathode current was found to affect the depos- ition rate of the material and AES studies indicated that emission line intensities increased in direct proportion to current setting. Other AES studies of such processes were carried out using oxygen thermal plasma evaporation (94/869) and argon or oxygen r.f. magnetron sputtering (94/1784). Several SIMS investigations of Y-Ba-Cu-0 systems have been carried out although these were primarily concerned with structural understanding rather than analysis (94/1403 94/1518 94/1551).The application of LMMS may also be of interest in this regard (94/1402 94/1462 94/2864). Laser ablation has also been used in conjunction with MIP-AES for the measurement of several elements in ceramic materials (94/289). Emission spectra were acquired using time-gated detection normalized by use of an internal standard and calibrated using reference materials. Thus Al Fe Mg and Si were determined in Y-Ba-Cu-0 semiconducting ceramic at trace levels. There have also been a number of reports of the application of XRF to the characterization of superconductors (94/118 94/335 94/2478). Two papers concerning the use of TXRF for the analysis if thin films may offer a view of potential developments in the field (93/3893,93/4053).It is worth noting that most of the XRF methods cited ICP-AES as a reference technique for validation purposes perhaps indicating why there are relatively few new ICP applications reported this year (94/1016 see also J Anal At Spectrom. 1993 8 337R). The determination of trace level impurity elements in REE oxides continues to be a subject of interest and despite the well documented problems of spectral interferences the great majority of papers published in this area related to applications of ICP-AES. Consequently studies of the effect of ICP operating parameters (94/1057) emission line selection (93/3529 94/43 94,4239) or spectrometer resolution (93/3559 94/497 94/1731) may be of passing interest but are unlikely to have broken new ground. A comprehensive listing of such methods is provided in Table 3.Spectral correction methods applied to ICP-AES determinations in dysprosium oxide (93/3951) yttrium oxide (93/4010,) and neodymium oxide (94/668) may be of more value. The most obvious method for avoiding spectral interference problems in the analysis of REE oxides is to separate the analytes from the matrix in a preliminary procedure. Thus extraction chromatography has been applied in the ICP-AES determination of trace impurities in scandium oxide (94/706,94/1613). The first mentioned paper was restricted to the determination of Hf and Zr and employed a Levextral resin with l-phenyl-3-methyl-4-benzoylpyrazol-5-one as the stationary phase and hydrochloric acid as the mobile phase. An enrichment factor of over 2000 was achieved.It was reported that good agreement with results obtained with spark source MS was demonstrated. In the second paper by this group 18 elements of interest were separated using 10 g of trioctylphosphine oxide-Levextral resin and eluted with hydrochloric acid. In the latter case some benefit may have been achieved in terms of sensitivity by using end-on viewing of the plasma. Detection limits in the range 0.08 pg g-' for Mn to 4pg g-' for Zn were given. Other examples of chromatographic separation for ICP-AES reported included the determination of REEs in terbium using a 2-ethylhexylphosphonate loaded polymer resin (93/3932); pet- roleum sulfoxide column extraction for detection of impurities in yttrium oxide (94/260); column extraction using D238 chelate resin for the determination of transition metals in lanthanum oxide (94/389) and separation of REEs on ammonium form cation-exchange resin using La-EDTA eluent (94/437).From the volume of papers published it might appear that ICP-AES is the technique of choice for the analysis of rare earth compounds. A paper discussing the advantages and limitations of FAAS ICP-AES ICP-MS and XRF may be worthy of attention in this context (94/2575). It was recognized early on in the development of ICP-MS that the technique would find particular application in the determination of REE. Isotope dilution is a technique which can be exploited to good effect in ICP-MS and this has been demonstrated in the determination of ultra-trace levels of Nd in high purity lantha- num compounds (94/2808). It was found to be difficult to separate Nd from lanthanum in 10-fold excess because of the closeness in mass of the elements and their similarity in chemical behaviour.However since ID does not require 100% recovery nor absolute isolation of the analyte this allowed separation procedures to be designed with greater flexibility. Thus Nd was detected in the ng 8-l range using the procedure developed. The most recent advance in ICP-MS has been the construction of high resolution magnetic sector instruments and these have now been applied to the analysis of REE samples. A unique high resolution ICP-MS system equipped with seven Faraday detectors has been used to measure isotope rations for Hf and Nd in REE samples (93/3402 see also section 3.3.1).The elements were present as major constituents in the materials. Good agreement with excellent precision was obtained in comparison with the accepted value for these materials. Further details concerning the determination of trace impurity rare earth elements in high purity yttrium and gadolinium oxides have now been published (94/576 see also J. Anal. At. Spectrorn. 1993 8 337R). Although the high resolution MS system was incapable of achieving peak reso- lution for gadolinium polyatomic species on Lu Tb Tm and Yb the use of doubly charged ions for measurement allowed this difficulty to be overcome. The instrument was set at a mass resolution of 400 which still provided adequate ion transmission for the measurements. The plasma power was optimized at 1200 W to maximize the production of doubly charged ions and the mass analyser acceleration set at 4.5 kV.Detection was performed by ion counting. Detection limits were reported in the range 0.05-3 ng ml-' for doubly charged ions. Where singly charged ions could be used LODs were further improved at 5-30 pg ml - ' . Electrothermal vaporization ICP-MS has been applied to the determination of Lu and Tb in gadolinium oxide (94/632). The principle aim of the study was to investigate oxide formation in ETV-ICP-MS. However under the optimum conditions which were established these analytes were detected at a concentration level of 0.01 pg g-' in high purity samples.354R JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY DECEMBER 1994 VOL. 9 LOCATION OF REFERENCES The full list of references cited in this Update have been published as follows 9313354-9314131 J.Anal. At. Spectrom. 1993 8(8) 377R-404R. 9411-94/614 J. Anal. At. Spectrom. 1994,9( l ) 1R-23R. 94/615-941960 J. Anal. At. Spectrom. 1994 9(2) 73R-85R. 941961-9411264 J. Anal. At. Spectrom. 1994 9(4) 135R-146R. 9411265-9411830 J. Anal. At. Spectrom. 1994 9( 5 ) 149R-169R. 94/1831-9412175 J. Anal. At. Spectrom. 1994 9(6) 189R-200R. 9412176-9412412 J. Anal. At. Spectrom. 1994,9( 7) 203R-212R. 9412413-9412867 J. Anal. At. Spectrom. 1994 9( 8) 249R-265R. 94/2868-9412994 J. Anal. At. Spectrom. 1994,9( lo) 307R-312R. Abbreviated forms of the literature references quoted (excluding those to Conference Proceedings) are given on the following pages for the convenience of the readers.The full references names and addresses of the authors and details of the Conference presentations can be found in the appropriate issues of JAAS cited above. Abbreviated List of References Cited in Update 9313355 Analyst 1993 118 297. 9313356 Analyst 1993 118 301.9313362 Anal. Sci. 1993,9,157.93/3363 Spectrochim. Acta Part B 1992,47 787.9313366 Spectrochim. Acta Part B 1993 48,7.93/3367 Spectrochim. Acta Part B 1993,48,25.93/3368 Spectrochim. Acta Part B 1993 48 39. 9313379 Talanta 1993 40,95.93/3380 Talanta 1993,40,107.93/3382 Bunseki Kagaku 1992 41 T151. 9313386 J. Anal. At. Spectrom. 1992 7 1167. 9313388 J. Anal. At. Spectrom. 1992 7 1195. 9313389 J. Anal. At. Spectrom. 1992 7 1201. 9313390 J. Anal. At. Spectrom. 1992 7 1231. 9313397 J. Anal. At. Spectrom. 1992 7 1291.93/3400 J. Anal. At. 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